Learn me: Simpson Hybrid S "HANS" device

So, thinking about picking one of these up because they work with "regular" 3 point belts.  This past Saturday was the first time in almost a decade that I was on track with a car that didn't have race seats, 6 point harnesses and a rollbar.  It felt really strange having to brace myself against the center console and the drivers door.

More importantly though, since I was only wearing the factory 3 point belt, I couldn't wear my HANS device.  I also do some instruction with NASA and most of the students cars only have 3 point belts as well.

So it looks like this Simpson piece will work in any car, regardless of what harness/belt arrangement they have.  Anyone using one?  What can you tell me about it?  Comfortable?  Run true to size?  Best place to order?

My last instructor let me borrow his (he was awesome).  My biggest gripe was that it restricted my arm movement when turning the steering more than 180 degrees while trying to maintain hand position.  The Integra I was in had a stock interior plus sunroof and subsequently had some other ergonomic issues when wearing a helmet though (I'm 5'11'' 200lbs), so YMMV.  Other than that it was fairly comfortable and I was glad to have it.

In reply to Matt B :

It doesn't have arm straps does it?  So how was it restricting your arm movement?

I have one and like it quite a bit. Pretty handy for hopping in any car that doesn’t have a harness. Only minor complaint is that it feels kind weird when you’re not in the car. The part that sits on your shoulders feels like it’s falling off your back when you’re not in a seat. 

If I put it back on I might be able to tell you with certainty, but it's been a while.  Looking at photos of the thing it could have either been the vertical shoulder straps or maybe just how the system worked as a whole.  It was wrapped pretty tight around me and restricted overall movement of my torso in ways I didn't expect.  It was simultaneously reassuring and aggravating.

In a different car it may not have been an issue.  I had to lean back farther-than-ideal to clearance my helmet enough and the steering wheel on those cars don't telescope to compensate.  It's funny the ergonomic things that you notice in a single 20 min session on track that you don't bother you significantly in years of autocrossing.