RE:engineering: You're spot on, on the engineering side it's dead simple. Simple, reliable, serviceable were all part of the goal.
RE:pricing: Other devices in this category are expensive and several have built-in synth engines and audio cards. This build uses mostly off the shelf components in an effort to keep the price down.
Instagram said I 'violated community guidelines'. Not sure how, I posted a photo of the controller and two videos of it in action. I think my error was following too many people too quickly, maybe lots of external traffic from reddit hurt too?