Hi Rikkis:

BACKUP=SET PLUS the user styles you may have replaced in the Factory locations Plus IF you have also change the STS/OTS on the Factory styles too, the backup does that, the set does not.

that is what the Backup saves besides all the things the SET does, and that is the difference between the SET vs Backup.

Assuming that you already have the latest OS and Musical resources, you could use the BACKUP as the MEGA-REGISTRATIONS bank.
This particular procedure, to me, seems much faster if you use lots of samples in User Voices, Drum Kits, very much like my friend from Croatia.
He particularly use the Backups as MEGA registration banks, that contain truly all his data for the kind of music he makes with all those samples in User voices, etc.
I use that too, because, I do not know if you ever got those messages when loading a SET, that the memory is full, well, that issue is gone if you load/restore your backup, the only thing you may have to do, is to turn the keyboard off and then on after the Backup have been restored.