I haven't seen anything on this, but is there a way to have what's shown in the Rift headseat mirrored to a GearVR? I have both and think it would be neat for seated experiences like racing or flying. Might make the other wearer nauseous given they don't have control of the view, but no different than a lot of VR videos out there and latency wouldn't be much of an issue given they don't control the movement...
