Just curious, what do you think the the state of balance would be if you nerfed pgs and kept shocks the same?
I think it would depend a lot on how you nerf them (either way would serve to imbalance the game but to different degrees).
If you made them come out later there would be a bigger window that soviet elite infantry (guards specifically) dominate which clearly wouldn't be good for game play. The reason I say guards is because in my mind pgrens are the counter to guards since you can't really roll light vehicles at them like you can shocks.
If you nerf their AI then shocks get better by comparison which again wouldn't be ideal because now so inf can deal much better with pgrens whereas ost now have an even harder time vs shocks.
If they needed the AT ability it probably wouldn't be a hard hit since German AT is superior to soviet AT already.
IMO if anything needs nerfing at all its the elite troop instavet everything bs ability.