It's like, I'm not really worried about if Johnny Depp can pull off a passable The Doctor, because lord knows he can be the right kind of crazy, but honesty I'm just not sure it would be any different than, say, Captain Jack Sparrow, if Captain Jack was 900 years old and had a blue box instead of a ship.
(Also, and this is entirely irrelevant, but I was watching The Trial Of the Doctor, Colin Baker Era, and he said he was around 900 in that one, so I'm kinda wondering what gives. Was his childhood 800 years long? Is the first regeneration the long one, then you get a bunch of short ones toward the end? Is Gallifrey in a Mercury-like orbit around a very cool star?)
I mean, I trust Davies to pull it off, but it's just odd.