If you search the site you may find a topic started by a member here that actually had a tubeless tire on a tube type rim that instantly went flat when the tire sipped off the bead, I think when he hit a pothole.
I don't really care what anyone else does, but I will never do that on one of my bikes. Sure, the chance of failure is maybe 1 in 800 or something, but those aren't good odds for me, my luck don't run that way.
