Yes, backup files can be restored between the GO:KEYS 3 and GO:KEYS 3 Minion, with one limitation.
GO:KEYS 3 to GO:KEYS 3 Minion: No restrictions.
GO:KEYS 3 Minion to GO:KEYS 3: The 32 Minions tones are not available on the GO:KEYS 3. If the backup uses them, the GO:KEYS 3 assigns unintended tones instead.