I had a 3 year-old hedgie, Max (RIP), last year who loved using a ball. He was a very large guy. Each night I would take him out, give him a snack, and after he pottied I'd place him in the ball. I can see how all of the issues everyone mentioned could come into play. My current hedgie, Prince, is still young and a bit unpredictable with his pooping so I'm not comfortable leaving him the ball.
Sarah
Sarah