First, a brief admission. My experience of FiF is limited to one game, which is currently at July/August 42. Barbarossa has just started. I have, however, played WiF for more than 20 years and have played almost every option available (except noZOC on surprise which I believe would need a map revision to be neutral).
Second, some areas of agreement. Yes, it makes the game a lot longer, and takes up more space. In addition, we have found that it greatly increases the chances of making production errors (although as we have become more used to the system these seem to have decreased markedly). But I do have some strong disagreements and have a completely different view of FiF as an optional add-on.
The Time Factor
When we started to use the FIF production we found it a bit laborious, but with a bit more experience we have speeded up considerably. Part of the delay was my desire to keep notes of all builds, both to ensure we were doing it correctly and for my AAR which I wanted to use to see how it impacted production over a complete game. After about 20 turns we have become quite used to it. Sure it still takes more time than RAW, but so do many of the optional rules. We also use the 3D10 table, various options re air combat, Devin Cutler's sub/convoy system etc etc. These all add some time, but we feel give better results and a more enjoyable game.
We play optional rules we like, and accept the extra time requirement. I suppose it boils down what you want to get out of the game. We seem to prefer games with lots of decisions and don't really hurry along. I know others who prefer to move quickly to get a result and have played with them quite amicably. However, I find I enjoy games with all the bells and whistles more.
To me the "Time Factor" is simply an individual matter, dependent on individual taste. I suppose you could say "If you like a quick game, don't play FiF" or "If you like a simple, uncluttered game, don't play FiF" and I would agree. But I don't think you can criticise an optional add-on purely on the basis that it adds length and complexity. It depends on what you (as an individual with particular likes and dislikes) gets in return that will determine whether you play a particular option.
We seem to like the opportunities and constraints that make production a bit more than just deciding which sort of counters to pick. I'll give a few more reasons below.
The Space Factor
Can't disagree - it does mean you have to find space for a few extra charts. But we have found that we don't get a good return (enjoyment - v - space) for the African map, and only use the Scandinavian map on occasions. So overall we are in front. If you use task forces you have to find some space as well, but I would not condemn that option on space grounds (in fact I wouldn't condemn it all!)
The Balance Factor
I am hesitant to comment too much on this as I haven't played a game through using FiF. However, I do have the following comments.
Balance is very difficult to discuss without a full analysis of every option that is being played. As far as I am concerned, it is nearly impossible to evaluate even a comparatively simple option in isolation. I have followed the extremely long and sometimes acrimonious discussions on the WiF Discussion Board about the balance of specific options and have decided that, depending on the totality of options used, something that may be seen as overwhelmingly helpful to one side or another can be fairly benign if certain other options are used. Rail movement is one example.
We play FiF with the 3D10 Combat Chart and with Offensive Points and a heap of other options that impact pretty much all the issues you raise. I am not prepared to say FiF is balanced, but then I don't think any option is balanced - all options have an impact, the question is what is the overall impact of all the options played. Like most others, we have a lot of horse trading before a game, with everyone having options they like or loathe, and generally we arrive at a bundle of options we think roughly balance each other out.
To be honest, we find the 3D10 Combat Table has a far bigger impact on balance than FiF, particularly in China. The ability to carve up less mobile units, and the ability to keep units in the field rather than the all or nothing losses in 2D10 make you re-evaluate both attack and defence. But that is another topic.
We accepted that some Russian disadvantages occur because of FiF. But with a bit of planning I think you can offset most of them, and there are production issues for the Axis as well. We have always had a real problem with units appearing exactly where they are needed most (You just lost the only fighter in Leningrad? Luckily all the fighters produced in the last two months will arrive there!) I am playing the Allies and haven't lost a unit to factory overrun yet and don't intend to, but if I do it will be due to my taking a risk and I'll live with it and accept in the same way I accept it when units are caught out-of-supply, or when I lose mobilising units in Brussells or Belgrade. It doesn't seem too far fetched to me that heavy armour production and mobilisation is not carried out near the front. There are some delays, but in my opinion these are offset to some degree by German production issues. No longer can Germany produce a unit at Konigsberg every turn. When Germany is producing a large number of ground units, they are produced all over the country - the factory stacking limits force this. True, production tends to be concentrated in certain large cities (seems fairly realistic to me), but rather than reducing overall fighter numbers, we find that fighters congregate around these cities as they are such juicy targets. The "Let's hit Lille every impulse with Allied fighters covering bombing raids " problem has disappeared (a real arguing point in our group!). The fact that GARR units appear wherever you like offsets some problems (reinforcing isolated or non-factory cities). What we have found is that tough decisions have to be made about what is produced where - and sometimes the Ministry of Economics does not let you do what you want to do - we like that sort of system, though I can understand that others dislike it.
With bombing raids, what we have found is not that the 12th SS is destroyed, but that its appearance is delayed. I don't have an issue with raids on (for example) Dusseldorf slowing production of armour units. We actually like it that bombing raids can target key units, and that as a result some production is moved to more easily protected cities. Yes, Germany has been pretty immune in the early war, but mainly bacause it has protected its factories with fighters. I take your comments about Paris and Lille, but have never been happy that Germany's war production was significantly affected by raids on those cities. I suppose it is a matter of balance and FiF shifts it the other way.
I do agree with your most of your comments re FLAK. I drew one as the French and it was a complete waste (although I drew one as the CW that has been a great help). That problem is easily fixed as you suggest - separate from Force pool (we will probably do this as a house rule next game). The jury is still out on the other issue you raise - we haven't yet got to the stage of massive bomber raids on heavily protected cities. I expect it will be interesting, but my gut feel is that Germany will be hard pressed to replace any FLAK lost (they may have other priorities) while the US will, as always, shrug off bomber losses and just keep hammering away. Overall I suspect pro -Axis, but I would like to see the effect on Axis production - yes Germany can build and concentrate FLAK around a few key cities, but factory stacking and other needs (closeness to the front, distance from bomber/escort bases) will also impact. But I don't see this as a game breaker, rather a possible handicap for strategic bombing. But then, whenever I have played as the Axis, I have always felt that the Allies had too much of an advantage in the Strategic bombing campaign. (Of course, as the Allies, I always feel this area of the game to be well balanced and historically accurate!).
Why I think we will continue with FLAK is that we find AA units are almost never used to provide factory defence - they are too expensive and too useful to sit around and, if produced, become front-line units. So really FLAK is an attempt to provide something other than fighters for protection of production areas. In our current game, they have actually been used more by the UK to dissuade and beat back German bombers (the Commonwealth is on the back foot).
The Realism Factor
Oh no!! I don't think anyone ever wins realism arguments. I can't fault anything you say, but then I completely disagree with your conclusion. I agree that units are not produced in a single spot, but then I have problems with a corps appearing exactly where needed most. Mobilisation and call-ups are spread across a country, with small units popping up at locations scattered around and gradually agglomerating over time. Over the years we have been concerned with the way mobilisation points move from one side of the country to another in an instant, and the God-like ability of the Minister of Armaments to see where units should appear. We have no problem, for example, with FiF Russia needing to plan ahead 4 months if it wants an infantry corps to appear in Vladivostok. What we find really annoying is that an armour unit can appear in Kiev if Germany declares war the turn before, but can appear in Vladivistok if Japan declares war (OK, not a good example but I am sure you get the point. Maybe a better example is a MAR in the USA appearing on the East or West coast depending on losses in the previous turn).
We believe that FiF is more realistic, you (and maybe the silent majority) believe otherwise. I think that a game can never be truly realistic and remain playable and enjoyable. Both sides can pick things that support their argument and go against the other side. What determines realism arguments (other than off the planet suggestions like a conquered Italy fighting on from an aligned Lithuania!) is what you enjoy and what really annoys you. So we seem to enjoy having to make additional production decisions while you don't, and I suspect this flows through into our realism arguments. We happen to believe that having to decide where to build your best fighters, whether to concentrate production in a "target" city and having to weigh up the benfits of production close to the front against the risk if factory overrun makes the game more realistic. I see some merit in your arguments why it is not, but beg to differ.
Just one small point though - being able to pay just one BP to start a unit helps the smaller nations - it has always annoyed me that Italy China etc have to salt away BPs to start a HQ or other large unit, or alternatively not produce anything else for a turn (if lucky enough to be able to do it in one turn). FiF lets Italy start a HQ on Turn 1, and the ability to turn production on and off we find a real benefit (and realistic? Sorry, couldn't resist). Having to save production points to build big units in effect increases production time - Fif does away with this (or more correctly lets you decide the length of time.)
Other benefits
One big argument in favour of FiF is the way it integrates with some other options. We are big fans of the 3D10 - after using it we could never go back to 2D10. Yes, makes the game a lot longer, but in our view much better than the by now nearly automatic calculations of odds in 2D10. 3D10 allows lots more decisions, impacts production (a real use for ART). I could go on, but you either like it or not. I believe there are still people using RAW combat tables - I find it hard to believe but accept that that is what they like. To each their own.
But if you do like certain other options, FiF is a good fit. FiF works well with 3D10 losses, it works well with Offensive Points rather than OCs, it works well with other options we play. If you don't like those option either, this argument will pass you by. If you do, then maybe FiF is for you.
Conclusion
My main point here is that using FiF will be a personal decison based on the way you like to play. Though we play to win (nobody wants to be a loser!), with such a huge investment in time we play for the enjoyment we get each session, not just a thrill and bragging rights at the end. I accept that you and your group don't find FiF adds to your enjoyment. However, we find that FiF, by adding a range of meaningful (and arguably realistic) decisions adds to that enjoyment, and (for us) the negatives are outweighed by the positives.
Congratulations on the Web-site and I apologise for the length of this post. I hope to contribute more often, but more briefly. And if allowed, would like to post my AAR of our current game, which includes all the production so you can track how FiF works in an actual game.