I don't get headtracking with a monitor setup. Don't you have to keep your eyes glued to the monitor while turning your head all over?
There's no discomfort doing this for a few hours?
No, not really. All inputs are accelerated/exaggerated, so a small head movement could mean a 90 degree or more head-turn for your in-game avatar. It probably would look funny if you watch someone playing with head tracking, but feels very natural after a few minutes. The only time it doesn't is when the acceleration curve is too low, and/or you're trying to look directly behind you in-game. In those situations, it becomes more obvious that you're turning your head one way but turning your eyes back the other.
I just put on my headphones with the head-tracking clip attached, pick a point on the screen I want to be my "centre point", press F12 to calibrate, and it's perfect. I always make sure to pick a centre point such that the side-screens aren't too low-down, if you have to hold your head down to look at them, it gets uncomfortable after a while.