These were discussed at length last month on the SWB ORC mailing list. Nobody there had any experience with them either, they are expensive. Only comment was the fact that you have to drill another valve stem hole in your rim.
BTW if anyone wants to subscribe to the mailing list (if you can't get enough of this stuff here) go to:
http://www.off-road.com/4x4web/faqs/tech/mailing.html

Brad
ORC Land Use Section Editor
http://www.off-road.com/land
Vice-Pres. Rock Garden 4 Wheelers, Farmington, NM
http://rockgarden.rockcrawler.com