The problem for me when using these headtracking systems is that they just work totally different than in reality. You only move your head while you have to keep your eyes focused straight forward to still see the monitor
, which feels weird to me. This is quite the opposite from what you do when looking around in the real world where head movement mostly only follows eye movement.
I can see that this is a good way to operate another controller axis without using hands or feet and you probably can get used to it very well, but it's just not for me.