Hi
This is an old post but since there was a recent post and I just saw this I'll comment.
I've been using 3D Vision for a couple of years now, and the motion sickness thing doesn't bother me any more.
I never had it bad, but now I actually forget that I have the glasses on, and sometimes play for several hours in stereo.
I like riding the roller coaster in The Secret World in stereo.
But as Trog69 suggested start with minimal depth and then gradually increase it as you grow accustomed to it.
Mike