Personally I don't care if he using external hardware or not, everybody does even in "modern" lives with laptops so it would be perfectly expected.
What I don't like is that everything is pre-arranged. He is mixing ready songs, not doing a live. he nearly never touches the Amigas for skipping blocks or muting tracks, only acts the mixer (and even never looks at the monitor!). He could have done exactly the same things by recording the two Amiga's outputs onto two CDrs and using two CDJs decks.
Nice vibe, anyway, and surely nicely produced sounds!