I get slight to moderate distortions depending on how fast/far I move my head (Track IR). I brought this up on another forum awhile ago, and judging from the responses most users get the distortion in FSX. You can go into the FSX.cfg and change your Dynamic Head movement values to zero, and it will help somewhat. If you do that, you will remove the involuntary head movement you get when putting your fast mover into burner, decelerating quickly, or snapping into a high-g turn.
P.S. I haven't tried the V-sync method, but I'm going to.