HTC vive / Oculus cross compile

I am working with both Vive and Oculus (the new one) and I have noticed that when using Vive the camera position in the scene is much higher than on Oculus. Does anyone know how the Y of the camera is calculated on both, and is there a smart way to make these the same.

Looks like the vive zero Y is the floor. I don't know how this is on Oculus.

Also I have noticed that when using the Vive, Unity water renders two reflections, one per eye, which both are wrong...