Backup and restore

Update:
I restored a course in 1.9+ today where I wanted to keep the forum "starter questions" posted by [generic instructor], who posts in all our multiply replicated courses.

During restore, I unselected all user data, then selected user data for forums, selected "none" at the bottom of the restore (where I was offered "course" or "none" for "users").

The forum starters were there when the restore was over, and [generic instructor] was a class participant, but the other users who were in the backup (but had never posted to a forum) were not carried forward into the new classroom.

Note: [generic instructor] is a global user in both our old and new server. Thus, your mileage may vary.