You mention changing the network ID manually in the db. In many cases a domain name would likely mean an email address change. I note that there is an email field and the users email is also one of the values in the xml ('settings' I believe) field. Would this xml also need to be updated or in what cases would the xml field need to be updated?
So currently the user sync feature synchronizes users and groups, but the login is Docuware (application login) and passwords are not linked--Passwords for users either have to be set or the user has to use the forgot password?