UnityEngine.VR.InputTracking.Recenter() seems to work differently for the Rift SDK than it does in OpenVR. With the older Rift setup (Unity 5.3) the recenter puts your head at the origin. With the new system it either isn't working at all or it's resetting it to the floor. My game is a driving game so when somebody resets the VR headset I need it to pop to the driver's head. This no longer works, instead it places the feet at the driver's head and you're now standing on top of that....
OpenVR - How to reset camera properly?
OpenVR - How to reset camera properly?