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)
OK how about we remove the mg34 in my proposal and give them stgs with ambush? Also make them 300mp but increase the upgrade cost.