Oh, thanks a bunch Naomi -- I wanted to comment on this!
500 posts is a lot. I realize this. Originally in my head, I was thinking, "How could a user change their user title before 500 posts? Maybe it could be given as a reward! For either working on the site, or reading Batman's blog, or making a walkthrough, etc."
We'd need a list of applicable deeds-rewards, but I think title changes are fun and should be encouraged, even at low post numbers. (Members with 500 posts clearly deserve them, and should be rewarded for their participation by being able to change them at any time)