I kind of prefer it if it changes everything, just because it keeps it consistent. In a major (well, serious posting with limited users) (i.e. my old site) forum site you identify the user by their avatar rather than bother reading the names. It is much quicker, although you get thrown when the user decides the change the avatar. You do get used to it again reasonably quickly, and then its back to normal. It it's not too much work, perhaps you could write something for the avatar changing page that queries the user as to what they would prefer to do. That way they get to have it the way they like it.

meh.