My feeling on username changes is this:
I understand that the name you pick when you signup may not reflect your future business.
I also understand a name you picked as a 16-20 year old may also not be what you want to be known as later on.
I also know that sometimes you start out as a person doing business and then turn into a business and want your username to match that business.
If a user has 100% feedback rating I am ok with doing a username change based on one of the above scenarios.
I am also ok with giving you a username of a dormant account.
I will never change a username for somone running from a bad reputation they had with the old one, my experience over the last 8-9 years tells me they will just abandon the account and start with a fresh username.
It also has a negative effect on a well know user when they change their username as most people will not relate to who they are.
-=DCG=-