How to transition User from local to LDAP (or passthru)

[devodl]

Current state
- Users have been created in Alfresco (4.0.c) using its local repository
- Local usernames are derived from the person's name (e.g. rwiggam)
- Users have created content and workflow tasks that are owned by their local account.

Future State
- Alfresco is being reconfigured to use either passthru (Active Directory) and/or LDAP
- Username from AD or LDAP is derived from the employee number (e.g. u123456)
- Users need to continue working with the documents and workflow tasks assigned to them.

Question
What is the best practice for transitioning the existing local user accounts to their corresponding LDAP accounts?
  e.g. rwiggam ==> u123456

An ideal solution would be to associate the new username (u123456) to the existing local account (rwiggam). The user would simply login with the new credentials but would still own all their content and tasks.
An alternative would be to transfer ownership of all nodes to the corresponding LDAP account.

Another consideration is scale. Right now we only have 20 local users.
How would you do this if you had 1,000 users?

All suggestions and opinions are appreciated.

[openpj]

I suggest to import the new users from LDAP and then implement a batch that could bind the new users copying their User Home folder from the old ones.
Then copying all the permissions for each space in the repository translating the old permission users with the new ones.
Finally removing the old users.

Hope this helps.