Mike,
We are just beginning to implement enterprise logins in our ArcGIS Online Organization. We have over 100 members in the organization, but many of these members 1) have no content and 2) have not logged in to ArcGIS Online in over 4 months. So I plan to delete these accounts before migration so that there are fewer accounts to migrate. But, I need to store things from their user information, such as group memberships and roles so that if they request to join the organization at a later date I can restore those things.
I am also working on writing a tool that allows an adminitrator to assign new users roles and group memberships once they have logged in for the first time. (We have set up our enterprise logins to allow members to log in automatically without an invitation).
ArcGIS Online is becoming a popular and important platform for our organization and we are trying to stay ahead of administration by scripting as much as possible. It would be fantastic if the ArcGIS REST API could keep up with the emerging technology. I still don't see any documentation on how to access credit consumption on a per user/item basis although I see the Activity Dashboard for ArcGIS has that granularity.
Heath