The SMG is one of the two most powerful weapons in the game, on par with the broken Pentagun -- maybe even better. With their negligible recoil, their ridiculous accuracy, their extreme rate of fire, and their high damage, they outdo every other gun in the game. If an SMG and an LMG go head-to-head, all things being equal, the SMG will win every time. I have not tested it with an assault rifle, but I don't see how the result would be any different. Add to that the fact a cloaked Recon can sit in your lap without you seeing him (even if you're looking for him), the game loses all semblance of balance.