Man, I don't think I would trust a 2 post that was not bolted to the floor. That has about a 1 sq ft footprint in the center of the car that could act as a "pivot point" if you got the balance wrong or got to agressive with the torque. I would NOT go near it with out jack stands front and rear. There is a place in Indiana, Scott something equipment, can't recall the name (advertise in all the photo traders ect, good quality tools) that you could probly pick up a reg. 2 post for that $$$ that lags to the floor. I would feel much more comfortable with that, you just would not be able to use the full height because of the ceiling. It sure looks nice for not having to dedicate the space to it tho.
Adam