I think you're right; I don't see any MIDI files for loops. There's usually MIDI outputs for all instruments/tools (such as his looper). The BOSS RC-505 that Frank uses appears to have MIDI output/can be used as a MIDI controller, but I'm assuming that, even if could be used as a MIDI controller, that it wouldn't separate out the signals from the different instruments/effects/loop sets/tracks (and even if it separated the loop tracks, if you were to group together two "things" (different effects for, say, percussion and bass), it wouldn't split those into separate signals/tracks).