While I don't get sick from TiR, it does cause a pain in my neck sometimes, even after just short use. Mostly from trying to hold still and keep the view in center/front and the sky in view I think, no matter how I set it up I find it moves around when I don't want it to, causing me to subconsiously try and hold my neck still. I use the center/pause button a lot for TiR, but even just dropping my jaw/relaxing my head a bit, boom, view moves to where I can't see, so I have to hit the re center button again constantly. If I move the deadzones away from the center a lot to keep this from happening, then TiR moves like crap for tracking cons, so then what's the point...
This is my specific concern with VR having never tried it - most of my AH experience is getting into fights with a lot of contacts around, which means a lot of rapid view movement - so rapid that I still flick TiR off as my thumb/hat use for the last 25 years will always be faster than using TiR for me, and more intuitive as well.
I'm happy you're working on it though at HTC for AH, one thing I think AH always has done better (not just one thing) than everyone else is the view system, how it works and how configurable it is, while still being straight forward. I wish other sims would just buy it from HTC, along with the keyboard/stick config system. Anyhow, TiR works incredibly well (even though I'm not that great with it) with AH view systems, so I'm confident VR/Rift will too.