As a player who got hit in the knee by errata ( i mean HIT) i gotta say that the most wisiest thing already been said.
Codanous wrote:
However, if that character was so nerfed or the player had lost the will to play them due to a rules change, I'd advocate letting them rebuild. No reason a player should play a character they don't enjoy. Not really a game at that point.
So i think that a rebuild may be done only if your dm agree with you that your character need rebuild, you may change all but race and the main idea of character, so at the end of rebuild you will be the same guy, just with other tricks.