Not really looked into this class but what's the most irritating player build have you come across. I guess camper may get mentioned along with TF silencer Cold blood etc for me run around can be irksome or QS but it's all part of the game
if the game is sniper heavy I switch to my shotty class with lightweight, toughness, tac mask and dead silence with an emp to deal with claymores/betiies etc.........it works a treat, I have the hate mail to prove it
toughness is only beneficial to the KSG because shotguns shoot pellets so even though u flinch it still does not cause accuracy to go down much. my perk 2 with shotguns is usually cold blooded or scavenger.