Wrapping Up the Move
At this point, I had to perform some minor housekeeping tasks, such as creating the group folders and assigning the right ownerships and permissions to them.
I learned a great deal by going through this process. The most important lesson may have been something that I should have known all along: A task will take twice as long as you think, even when you take this rule into account.
The other lessons included the importance of backups and trial runs. Being able to quickly roll back to the earlier ASIP when we ran into mail problems saved the IT team a great deal of embarrassment. Having a couple of practice attempts at installing OS X Server gave me a lot more confidence and knowledge for the migration.