One thing I've found though is on hardcore I almost always play with a silencer, and feel it's a necessity. But in normal games I feel like it leads to too many assists/stolen kills. Kind of makes sense though, since the drawbacks of a silencer are negated in hardcore. It seems people are especially adept at seeking out the source of gunfire on hardcore, and hiding the muzzle flash is the biggest advantage probably.
^^ I am never using a silencer in hardcore. The way I play I use a famas with dualmags and put hardend pro on. SHOOT EM THROUGH THE WALLS!!! ;) Works perfectly. Cover is practically nonexistent and with dual mags you can empty a clip into a wall two or three times (and kill one or two enemys in the process) and still won´t have to worry about ammo.