I've done some limited work using the X-Box unit with drivers and software from the "Hack Kinect" open source group. Works fine. I can't justify the price for the iPi software. There are a few things to think about though. Facial recognition isn't gonna happen. Fingers or toes either if this makes a difference to you. I have no experience with the desktop Kinect. You can use an adapter from Nyko if you need to work closer than the "sweet spot" 8 to 10 feet that the Kinect likes to work in. The Kinect is essentially two USB cameras and a mic. One camera is IR and the other colour. The combination of both images is how the MoCap is done. Simple concept when you think about it but that is why no fingers, toes; or faces. The newer desktop uniy may solve the facial issues but that is only a guess baed on it's shorther focal length.

pdg