Roger came to our music hackspace in Shoreditch to show us how he made
it. Inside was guess what.... a RPi. Loads of cool ergonomic/haptic
ideas that make it very playable.
Now I remember the conversation went on to "efficiency" and Roger definitely comes from the "optimise for glory" camp. Told a story about how the Linn Drum machine was really less that 8 bits and used some trickery to squeeze out quality at a time when cheap 8 bit DACs were not a thing.