I only ever use silencer on an SMG where I use my "Super Syco Ninja" class. There I try and flank the opposition as much as I can, perks are Marathon Pro, Cold Blooded and Ninja Pro. This is I think is a good tactic if you want to get a ton of kills but if you aren't very accurate with a silenced gun and are not accustomed to sneaking into the enemy spawn unnoticed then you are in for a bad game