While I liked John Hurt as the War Doctor, I'll always think that if I was Moffat, I would have used McGann and showed how the Time War changed him from how he originally appeared in the movie. Rather than having a previously unknown incarnation that the Doctor tried to forget, it would have been just that the Eighth Doctor started off with promise like all the rest, but went down a dark road as a result of the war ("Night of the Doctor" really kind of showed how it could have begun, IMO). In the end, there still would have been a redemption of sorts and a partially shown regeneration into the Ninth Doctor.I'm not sure that would serve much purpose... but I'd love it. Might've been too fanwanky, but would've loved to see it.Just had a thought.
How well would fans have regarded it, if Day of the Doctor had featured McGann instead of the War Doctor and then regenerating mid episode into Eccleston who finishes the story with Smith and Tennant?
The introduction of Hurt didn't serve much purpose either. At least established regenerations would have been respected the way Timelord_Victorious describes it. I too have thought that this would be a good way to do it.