To be quite honest, I really don't care who gets cast to what role except for Sazed. In my mind there is only one person who should play him and that is Christopher Heyerdahl. If you have not seen him, watch Hell on Wheels. He also had a bit part in Chronicles of Riddick.
Shave his head, put some robes on him and with his weird lilting accent and 6'4" height, he makes the perfect Terrisman.