I've also gone.. I weighed about 240 pounds at the time. I also had a fantastic time - SUPER fun and scary!

The boats are immense, solid things that you could NEVER flip or even move when you step in - definitely not an issue. All that's very easy. My only issue was this: (kind of embarassing)... but we were supposed to all wear wetsuits where I was as the water was pretty cold. They didn't have any larger size suits available, and I'm all in the hips with my weight, so I could tell by looking at it that there was no way I was going to cram myself into the suit. So I was the only person on the tour who didn't wear one, and I felt a little conspicuous. That said though, the water wasn't that cold - in fact, on the last stretch, when we were out of the rapids, everyone had the option of jumping in and swimming beside the boat until we hit our landing point. Both DH and I did - so it really wasn't an issue safety-wise.. really, I just felt that it pointed me out as the 'one who didn't fit the wetsuit'. Oh well - I still had a great time!