I also forgot to mention that there is a great thread on Rennlist about the Hans and seat belt slipping.
http://forums.rennlist.com/rennforums/s ... p?t=209586
In that thread a relatively new fact arose. The Hans device was designed and built for race cars. In order to obtain the efficient performance of the Hans device, the device requires a more holistic view of the cockpit area. Meaning that lateral space is restricted by small cockpit cars or wrap around seats, etc. Most of us do not have Nascar like seating environments and the Hans, for those venues (F1 and NASCAR) formulated their H&N restraint system around having all those other "amenities" of safety. Again we do not. So folks have found this out and have not only had to purchase the Hans Device but also began modifying their cockpit area to help round out the environment the pro's have for safety.