Point of the USF Redesign for those who thinking it's meant to create a power imbalance is to add more diversity to the USF forces and give them more options, while still having their own unique structure.
-Unit placement for the Stuart and AA HT were meant to give each tier its own set of tools and play styles. LT is focused on offense, Captain on defense. It makes no sense why one building needs two suppression based units where Captain can't defend its own team weapons from being overrun by infantry.
These two don't jive with each other.
You have got to be aware that by switching the AAHT and the Stuart you're stacking LT tier. (Unless by increasing build diversity you're expecting players to be teching first for just AT guns? Investing more for pack howies and an AAHT that comes out later than it currently does?) Captain first is just a clear dead end. I mean, why invest 20 fuel to unlock a 50 fuel unit to defend your team weapons when you can just invest 35 fuel to unlock a 0 fuel HMG that also comes with a free infantry squad?
People go AAHT because the 140 fuel to get a Stuart after going LT currently is foolish. The AAHT is the available unit that can bridge USF players to Major. It is effective enough to deal with the OKW AAHT and Ostheer's 222s and halftrack. It doesn't hard counter, but it is enough to buy the necessary time. The only non-backtech thing Captain has ever offered was a rushed Stuart.
This "0.5" teching for LT and Captain I think is a good idea, and it may prove to be quite beneficial to USF and the game as a whole. It'll open up a much more diverse set of builds that get to not only use elite infantry squads, but also the many light vehicle callings that USF has. By going just LT and Captain (which means forgoing the stock vehicles), the Greyhound or the M3 HT would see more potential value. Incidentally, I wager free officer squads make it harder to field non-riflemen than anything.
But switching the AAHT and the Stuart just serves to reverse the very goals you're purportedly seeking. It'll always be LT first, with a decision to rush a stuart or go for an ATG.