@cephalos
pop upkeep, production speed, general cost for example.
I agree that it would be better if armoury upgrades, the ones that actually replace units, would simply give an option of building these better units, instead of just replacing the previous\obsolete. However, it appears to be a massive change ('though, on the other hand, I am not sure it is that much of a massive change), and I'm not sure the mod needs to get yet more complicated at this point. I mean, there are so many unsolved issues and unpolished aspects (reward units, lack of animations\animators, new Brits, Ostheer coming etc.). Probably, it would be better to concentrate all the efforts elsewhere.
Just my humble opinion.