I find it hard to envision a flaw that would tie a PND to a particular account that wouldn't be preserved in a tar of your home directory, so I don't really understand why reflashing then untarring into your new home directory is any better than creating a new user, moving the contents of ~ across, and deleting the old account.
Anyone have any idea what could cause a PND to be tied to a user account that would be avoided by reflashing?