I've been on a number of trips with Bill (one 5 day trip, three 2 day trips). Always a great time, and he will push you to try things you wouldn't try on your own, but always with safety in mind. It will be far more scary in your own mind than it will be in reality.
I've seen one factory air dam torn (never a good idea to wheel with low hanging, frivolous body parts) and I've seen one very slow speed flop-over. Calling it a roll-over would be a serious overstatement. The driver took a very bad line (shallow angle of attack) coming out of a stream-bed crossing and flopped over. There was some minor body damage, and one window broken.
His trips are well worth it.
SMB-less as of 02/04/2012. Our savings account is richer, but our adventures are poorer.