Using a simple test scene with just a few primitives, the following sequence of actions either crash the Unity Editor or leave the Rift goggles blank (even though head tracking works in Game view). In one case where the Editor crashed, subsequent attempts to launch the Editor with the test scene crashed upon launch or upon attempts to enter Play mode; I rebooted the computer to recover.

Connect your Oculus Rift to your computer.
Use Unity 5.3.3p1 to open a simple VR-enabled test scene.
Enter Play mode.
Power off your Rift goggles.
Set VRSsetting.enabled false via API.
Power on your Rift goggles.
Set VRSettings.enabled true via API.