Most Quake pros, obviously if you can control it it's fine I guess. Fatal1ty uses 2.5 for CS and 3.5 for Quake at 400 dpi.
AGENT uses 1800 at 3 sens, and 2 for cs (which is still high mind you)
cYpheR when he played cs, used 2.8 sensitivity (iirc) and he uses about 4.8 in Quake with Accel.
Even DarK (old cs 1.3 player for SK, eoLithic), used about 4.1 in Quake and 3.2 in CS, he ended up winning a CPL in 2002.
It's a common trend...