Live Mixed Reality Questions

Does anyone have a status update regarding mixed reality? We’re showing at a few events in January and want to do live mixed reality. We’ve got a Sony A7S, 18mm prime on a gimbal.

Does anyone know if multilayer (foreground and background) is working well yet? How are people mounting the controller to the camera? Is a cage the best way to go or are you using the hot shoe? Are you using wired HDMI?

Interested in this as well, mixed reality has been promised for some time now. I saw a guy doing it on youtube in UE4, he was experimenting though.
Can you connect three vive controllers to one game, to map one of them onto a camera?