So, I decided to just do a quick and dirty implementation of the controller with the knobs hardwired so that I could take it to 23b Shop to show to folks, but unfortunately, as soon as I started trying to send knobs over serial, it started crashing hard. I'm not sure what the problem is yet, but I am guessing that I'm overflowing the Arduino serial buffer. Perhaps I am polling the knobs too much?
In any event, I've been straining kinda hard on the edges of the capabilities of the MEGA 2560 (printing status to the console slows MIDI output down tremendously) and so I started looking at other Arduino alternatives to see if I couldn't make my life easier. As it turns out, there *is* the Arduino Due, which has similar specs to the Teensy 3 in an Arduino Mega 2560 shaped package. Like the Teensy 3, it is a 3.3V device, so I'd probably have to change the values of the resistors on the board, but otherwise it should be able to handle my project easily, without laying out and ordering new boards. Even better, clones can be had on eBay for about $15.
It seems worth a shot, so I found an experienced seller and placed an order. I won't see them till June (yay, China shipping) but I'm looking forward to having a lot more processor and memory to play with for the Twister project. I even ordered a 2nd board to see how well it handles an implementation of the NanoEgg Synthesizer engine.
I'm still gonna keep hacking on the Mega 2560 version, but if it works out I might switch to the Due for the release implementation.