A large part of our FPS experience revolves around manipulating the player camera. Since the Rift would essentially put the function of the mouse on our heads,

A large part of our FPS experience revolves around manipulating the player camera. Since the Rift would essentially put the function of the mouse on our heads, we could free the right hand with just a trigger or two triggers (one for alt-fire). The left hand can now comfortably use a WiiMote like remote, or a nun-chuck like controller. This setup would NOT break the previous control-model that the player is used to, since you can always switch back to disabling head tracking and using the mouse/keyboard combo. I'm pretty sure that this would increase immersion.