I am looking for the same answer. I imported and merged some AD GPOs using SCM and exported the combined GPO from SCM. I go into GPMC, create a new GPO and tried to run both "Import Settings" and "Restore from backup".
"Restore from backup" says "backup not found" in the directory I gave it. "Import settings" shows the GPO after giving it the directory with the exported GPO. At the "Scanning Backup" step it says that the Backup contains references to Security Principals
and I should specify how the wizard should translate these references. I even created a migration table, but at the final step it says "GPO: <Description> Failed" followed by "The data is invalid"
This might work for you though @KHanley if you don't have user rights assignment and security identifier stuff in your GPO.