This would only be my own uneducated opinion but I would imagine that Will Young has had far more experience and training then Gareth Gates, plus given his affliction it would be an absolute disaster if he lost his nerve.
I can not believe that he won song of the year with un-chained melody, what is that all about?? he mimed that too... An absolute outrage for the British Music Industry. (I'll get off my soap box now!).