A test migration and run of the script was successful; however a question came to my mind after the support case was closed.
The support person mentioned that multiple runs of the script may lower success rate for migrated VMs. For migrated VMs that don't work properly with the script, obviously self service FLR operations will not work for the older pre-migration backups. What would be the best approach, if any, for getting files restored from pre-migration backups on to the migrated VMs? Will users with appropriately configured roles be able to "Download" files locally from the pre-migrated backup chains? I'm wondering how to forewarn users what needs to be done for FLR from pre-migration restore points if the script didn't work for their VM.