PGrens are not as good as their counterparts for any of their roles:
AI: Grens with LMGs/G43s and rifle nades - far more effiicent.
AT: Pak40 and Grens with fausts. - far more efficient.
PGrens are a manpower sink for people that want to trendy or dare to be different.
The solution would be to make it so they have a defined role past just being a jack of all trades master of none. Or make them much more powerful but at a greater cost.
A rework could be:
PGrens cost 400 manpower, are deployed with 2 kar90 2x stg, and traditional stick grenades.
Have one of two upgrade choices both for 80 muni or 40 muni if vet1:
AT upgrade
One panzerschreck, anti tank grenade (only stuns), teller mine ability.
or
AI upgrade
1 x MG34, bundle nade, and booby trap ability.
Stormtroopers have the same problem as PGrens. In fact a lot of the problems in this game have stemmed from ill defined elite infantry, and balance being tied to poor design. Extensive reworks are probably necessary. I consider penal batallions as a product of an extensive rework, where they now have well defined roles, although Strafniki are meant to die not be elite 
Why i don't think it's a good idea.
1/ it suppose to be a closer combat unit, effective at short/mid range. The design is to ostheer have all noncommander kind of infantry. Making them long range (like obers) would be a. too similar to okw faction b. would overlap with grens)
2/ with upgrade it's a mobile AT, not very accurate at long range - yes but can do bigger damage than a pak, cannot be flanked and can be more sniky. Pgrens aren't suppose to be "A" move AT gun that kills any vehicule on their way (we had that with shrek volks blob and that's enough), their role here is diffrent. (though stun nade or teller mine would be pretty cool)
3/ There AI role is to be a flanking unit, not a "A" move squad that wins in every engagement in any range (like guards xD ). This unit needs better micro and that's why it's not very popular.
IMO becouse this unit is very specific it should be just cheaper: 300mp or so. Then you have more atractive hard T2 strat with skipped t1. Giving it more durability would risk with making it unkillable monster.
Making it even more elite, stronger as you propose A_E (therefore increasing price) would close the possiblity to skip t1 and go T2 to have a diversity at the begging of a game (like Penals in soviets)
Relic Entertainment
