Never ridden them personally, but I did see a demo once where a guy rode straight into a curb trying to pinch flat, seemed to work well(although modern tubeless systems kind of render this obsolete in a way).
Current custom builds: FG=KHS Flite 100 DH=Transition Blindside FR=Transition Bottlerocket
Well I picked up a used wheelset with tires for a pretty good price. Bought some tubes and the valves just weren't long enough in combination with the plastic/rubber strip. Decided to pull that off and run the tube without that strip. There's still a flat metal ridge below it, but with rounded edges, so we'll see how it goes...