I spent the last two seasons happily using tubeless Stans NoTubes ZTR 755 rims with Hutchinson Bulldog tires and Stan's sealant. It worked great and I could keep my tires at 25-30psi while weighing around 200-220lbs myself (pinch flats happened all the time to me before going tubeless).
Well, after a couple years, I finally destroyed a Bulldog tire on some sharp rocks on a course that cut through the tread. I bought some brand new tires and they say they have a carbon bead like Hutchinson advertised at Interbike this year.
After an hour of wrestling with the tires, I just barely got them on the rim, and half an hour later after putting about 30 psi into them, the bead just sort of exploded off and the tire ejected itself off the rim.
I think I might be going tubular finally, the new tires just feel too small for Stans rims now.