vorpX 0.9 will require the Oculus runtime 0.7. Extended mode is still available theoretically, but since it’s disabled by Oculus there is no way to use it anymore with Oculus headsets.
Witcher 3 currently has a very good Z-Buffer 3D implementation, there wasn’t time to check G3D feasibility yet and due to it not being a genuine first person game there are others with higher priority. What I can safely say though is that this is one the games where you *REALLY* should choose Z3D even if both modes are available for performance reasons. The best 3D doesn’t help a bit if a game can’t run at decent framerates with it.