I didn't really understand your entire post but this is a very good idea. It's pretty silly that someone who properly micros a tank to save the vetted crew gets penalized in turn by being forced to have a unit that eats up pop and can basically only cap and repair crits.
Sorry for my broken English,to summarize,I hope all squad have fixed population cost,so some upgrade or vet bonus increase squad size will not use one more population.So will not have chance lose one or two infantry to have one more big thing.