Any easier tips than reinstalling per the CallManager upgrade/configuration guide? We're moving mail stores to the corporate Exchaneg organization from a private domain on-box Exchange server
Sorry, you have to bite the bullet.
If you only have 1 server then you are looking at a day of downtime to do DiRT backup, Rebuild server, install Unity, test , Dirt restore and test again.
It's easier (and less risky) if you have 2 servers (failover) where you can take the Primary out and rebuild it as the Unified server while the Failover keeps running for users.
It's also faster if you tell users they will start fresh with no messages, avoiding the use of the Exmerge part of DiRT.