i don't know im not in the loop enough but I do see a potentially big problem. That it makes the gren have 2 seperate grenades (unless one replaced the other or they shared cool down times but then it might feel like whats the point of having 2 nades) which means nade spam.
I'm with Daspoulos on this, I mean you see three different grenades USF with smokes, AT-rifle, and frags and the limiting factor is the munitions available.
I don't really see what would be wrong in giving Ostheer the added versatility in their baseline rifle infantry. It would keep Allies from being able to bully in the early game if it's available right off the bat and spamming it would delay LMG-42's by a lot.