At Vet 1, Pumas get Aimed shot, which easily kills snipers since it never misses.
I never tested this ability on snipers. It would be amazing if that really works. Does it kill only one model though?
Regarding M3/Snipers/Guards against OKW: I haven't had enough experience to comment on the balance in this particular matchup. But i can say one thing for certain: I really dislike to play as OKW against it. This hardcounter style of gameplay shows CoH2 in it's worst from. Basically you have to go all-in with a vehicle other than a Kübelwagen and hope the enemy hasn't layed mines or buttons you. Surprise Falls/JLI can work also, every other thing (leIG 18, Stuka) is not that reliable in my opinion.
Limiting snipers to 2 sounds good to me. Or at least make them killable by a moving Kübelwagen. I want to see snipers as support units, not as a main army with Guards as support.