Originally posted by Copper Nicus
I seems like an idea, but AI's will be stopped by that even more. Right now AI got ablity to build most of it's historical units (in case of France at least), while humans have to work hard to get more than that.
True, same goes with Italy. But to be honest, I not worked on R&D ratios and priorities of those nations - I focused on the mayor-mayor nations. IMO many problems can be solved by the right R&D paths. But not all - in case of France AI will use only 25 IC for R&D (50%), so it has to be focused. And every new unit AI builds, supply use rise, so 25 IC will be only starting value... 
But there is difference between historical goals and playablity goals.
If we want make France historical, we have to focus on:
Air (light + heavy), tanks, navy.
If we want make France challening, we have to focus on:
Land doctrines, Infantry, Artillery.
In case of France I prefer historical appoach, since they are suppose to be easy prey.
What do you think?
I agree with your reasoning, and end goal (I want a historic approach as well), but I don't feel that we necessarily have to sacrifice certain aspects to get it.
I have been able to drastically increase AI research in peacetime. I limited the starting MP, and monthly MP gain so very low levels. The AI doesn't have any MP to build untis like Infantry Divisions (which eat up a lot of IC and later supply), so it actually spends a much higher % on Research. I have seen AI nations go up to as high as spending 100% of all surplus industry on research. France could get up to about 50 IC devoted to research (up to about 80 when all ships are done), with production limited to just ships that are being built. However, even with this increased IC toward research, they still are behind in areas that they should be higher in.
Correct R&D paths, as well as reduced IC costs can even the playing field, but it only goes so far for minor and minor-major nations. The thing that I have noticed is that the major-major nations tend to be 'ok' in regards to technology (even there we have some major deficiencies), but everyone else just seems to be backwards, including France. The nation that tends to do the best is Germany, but this nation also has some of the highest IC in the game, and also tends to have more technology in 1936 than most other nations.
I would perfer to have time restraints improved so nations cannot have advanced technology too early than to limit starting tech for all so no human player can abuse the system, but you shouldn't have to abuse the system to get what you should get, we should reward following the correct path.
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One way I was thinking about rewarding a balanced tech research program is to have it work in phases. You have a long period of time where you invest time for little reward, then you have a quick period where you get a lot. This is already in place in HoI, but currently it not only takes a long time, but it costs a lot too. I think that if we increase the time by about 1/4, but drastically cut the cost (by about 80%), then this would limit nations speeding ahead, but not limit their ability to research.
This would balance things, as even with Germany if you have 100 IC to devote to research, and all you have are these transition techs (i.e., "Basic Tanks"), you will spend only about 40 IC to get all of them, but you will still have to wait 360 Days. Larger minor nations could also afford 40 IC for 360 Days, and won't be left behind significiantly, since they all have to wait 360 Days. Germany will eventually get ahead, but not significantly.
This would stop abusing one field, since while you were working on level 4 tanks (at level 1 for everything else to get this) , everyone else has level 2 techs in all other areas. Level 2 techs are significantly advanced over level 1 techs that your Infantry and Air Force is getting stomped. Sure, you have great tanks, but you heavily sacrificed a balanced army to get tigers in 1942 (since mimimum time limitations will make it completely impossible to get them in 1939).