The
video demonstration on their site is definately worth watching (I was considering posting it myself, thanks for starting the thread). For injuries, I'm concerned about positions like that last one you posted, where she is rocking backward. Tilt a little too far, and that's a hard bar to the throat.
Also, as a guy, it doesn't seem that I'd be getting full penetration with any of these postitions, and I think that would be frustrating.