I have a QH/TB and a OTTB. Both of them I barrel race with. My OTTB has a harder time gathering herself in a small arena, but we're working on that. They are trained to reach out and run, but getting her to gather up faster in a smaller arena has turned out to be a task, but she is doing well. I think that as long as they enjoy what they are doing, they will excel. And, my grandmother has had two horses off the track and she barrel raced with them at the rodeo level, and she always did very well with them. So, imo, as long as they enjoy it and are trained preoperly, they will do well.