It always seems so cheap to change one's username. I think that if you do you should start over unless you have a good reason for doing so. If you're only changing a letter (like Adam did) or capitalizing or removing an underscore, etc... (Lucid Seeker) then that's cool. It's the complete name change that makes things confusing for other members.

I was part of another forum for a year and it was prime breeding grounds for constant name changes. Some people had new usernames every week/month. I'd get a PM or post response from some one expecting me (and others) to know who they are. When that stuff becomes status quo then it gets annoying. I don't see why you'd want every one to suddenly not know you.