I don't have an exact number, but let me answer your question with another question — why else are the most popular VR games (Beatsaber, Alyx etc.) either completely static or move-by-teleport? My suspicion is that they were playtested _ad nauseam_ and this showed significant portion of the players to be affected.
> I can definitely feel off at 60Hz, but no problem so far at 120 if the latency is kept to a minimum.
This is a common misconception and the type of nausea I'm talking about has nothing to do with the screen update latency or head tracking latency. Strongest effect happens when you're mostly stationary in the real world (sitting or standing on the floor) but moving in VR (let's say riding a rollercoaster). In this case, your vision tells your body that you should feel acceleration/deceleration, but your inner ear tells your body you're completely stationary. This is a contradiction commonly associated with intoxication and body deals with it accordingly.
I accept that strength of the effect is different for everyone, for me personally when I tried the rollercoaster demo on Quest 1 nausea lasted for 2 hours (!) despite the fact that I was never seasick in my life before.
> I can definitely feel off at 60Hz, but no problem so far at 120 if the latency is kept to a minimum.
This is a common misconception and the type of nausea I'm talking about has nothing to do with the screen update latency or head tracking latency. Strongest effect happens when you're mostly stationary in the real world (sitting or standing on the floor) but moving in VR (let's say riding a rollercoaster). In this case, your vision tells your body that you should feel acceleration/deceleration, but your inner ear tells your body you're completely stationary. This is a contradiction commonly associated with intoxication and body deals with it accordingly.
I accept that strength of the effect is different for everyone, for me personally when I tried the rollercoaster demo on Quest 1 nausea lasted for 2 hours (!) despite the fact that I was never seasick in my life before.