I just raised my sensitivity up to 4 (from 2), makes a world of difference when you see/hear someone off to the side of the screen and need to get your gun pointed in that direction asap. Also good for those "oh shit" knifing moments where you're first knife misses as they run by, you can typically turn around faster and knife them again.
Very hard to get used to after playing for so long on a lower sensitivity, but slowly getting better
Very hard to get used to after playing for so long on a lower sensitivity, but slowly getting better