OR is going to have trouble going mainstream given how different people react differently and the lack of research into long term use, but it might end up being not much more expensive than Track IR and does something similar so maybe it will survive as a quasi niche-item, like high end video cards or racing wheels.
For some reason I could play non-stop without issue. Demo after demo... the friend who bought it over was shocked as they only survived 2-4 minute bursts while getting used to it. I also didn't get the full impact though. The 3d is flawless, but other than that it was a screen 2mm from your eyes that somehow maintained focus and had annoying borders in the periphery (like snow goggles). I had trouble feeling as immersed as I was expecting.
It was calibrated for my friends head/eye separation and whatnot as well so maybe my experience was not unique. Apparently it works fine with glasses, you just move the lenses further from your face and wack your spectacles in-between. Still does some things better than a monitor though so I will definitely get a 2nd or 3rd gen release once the ergonomics are nailed down and the resolution and head tracking are sorted out.
My wife was sick for an hour after the roller-coaster demo, wouldn't stop reaching out to touch stuff and was visibly freaking out about the height. So I'm kind of jelly. She has though avoided games since the 2600 so separation of the virtual from the real is probably a bit more difficult for her.