Trivia time, and anyone can correct me if I am wrong, but I believe tree workers are the last guys OSHA allows to ride the ball, "if in their estimation, attachment to the lifting device is less dangerous than ascending the tree in question..." or words to that effect.
I have jumped through that loophole plenty of times, lol. " That tree looks a little sketchy, I should probably just ride the ball up..."
Having said that, there are definitely situations where riding the ball is a safer alternative. I have ridden the pick down, when the tree is just that unstable... lower me down, let me set a couple slings, and then I would reach out and cut the pick away and swing out with it, and then rappel down once I was in a safe spot... those were the days I earned my pay, lol