I have now changed my name several times. I started out in November 2006 as Chrysalis, and when I changed to HollyBlue in January 2007 I actually created a new account and stopped using the old one, because I wanted it to be clear which posts I had made under the old username (before leaving my ex-husband) and which posts I had made under the new username (after leaving my ex).
When ArtfulDominant and I got really heavily into the Master/slave lifestyle, I had my username changed from HollyBlue to ConsensualSlave. Then, finally, just a few days ago, since I no longer live in a slave role, I had my name changed to Belly_Dancer to represent best who I now am. I really hope I don't need to change it again.
I don't think it matters too much whether people connect my previous identities with my present one -- many people on the site came here when I was taking a long break from posting anyway, and didn't know me under the old name. Those who did know my previous incarnations seem to follow the changes well enough.