I'm sure the gods of karma will come 'round and smack me in the ass for saying this and not knocking wood... but... I'm one of those people who've never owned diskwarrior and have never even used it. I dunno... my upgrade experiences have nearly all been quite satisfying. There was one update I recall where Apple screwed things up a bit, but it was recoverable.

So, there's obviously something different (in my mind) between our installs or usage models.