Peter and I developed several different approaches to tech and did some playtesting as well.
What I found to be most promising and fun was a system where a new facility is introduced that concerns research. Research would also be specific in that you choose which research-project(s) to develop. Several research-projects can be pursued simultaneously.
We tried having the dice from facilities to be obtained for free or having to be purchased (funding) for something like 1-3 IPC. I believe the latter is to be prefered.
This would be combined with a dice-system where a research needs to meet a certain amount of points and different research-facilities give different numbers of dice for the research.
A research could also be developed with full or partial success. The partial success gives access to the tech, but with a nerfed effect, with the possibility of completing the tech later on.
One delicate problem was balance. It takes a lot for research to beat units in the field, so finding the right pricing is an extensive task. If it’s too expensive it’s just bad and if it’s too cheap it’s too good.
A system like this may most certainly include nation-specific research. I’d also prefer to see more projects available rather than fewer, giving more options for variety. There’s also the possibility of locking up certain researched based on either turn or previous completed research.
Of course, a tech-system in A&A shouldn’t be too complicated.