The stens are not 'fine' due to the broken ambush modifier in live, it and they are fixed in WBP and makes ambush very lethal.
You just have to get in the enemies face to use them, I love using them as they allow you to be really sneaky and get in a lot of wipes, anything above close range and I don't bother with the engagement which is, I suppose, how they should be.
Almost instant wipe out from camo does not actually help game play and that is why Wer camo bonus was nerfed (and is further nerfed with WBP camo changes.
Actually you do not have to be close they have the same DPS up to range 10.
They are far better than Shock PPsh at range 20.
Smg actually should be weapon that are good only at close.