i have seen them and ran in both 4pokes and 2 strokes. seen 1 fail in a cr250 (sloppy bore) and was ridden by a ex mx'r wide open for about 45 minutes before it broke the skirt.
i ran them in a "get me by motor" fresh bore. ran them on alky and didn't cut them any slack. fast trials, dunes, etc and never had a issue with them. they looked brand new after 6-7hrs ride time so i re used them in my wife's banshee.
i would say conditions right they should hold up well. well setup bore, proper tune, and no over revving the piss out of it.......