Andy, a shaft-encoder version of the 'furkled' stepper motor arrangement ended up as the 9K/"A"-series machine control panel wheel.
It can be a scrub wheel for frame jog, a detented wheel for shuttle, a multi-detented wheel for shuttle (additional detents at 2x/4x/16x or whatever), and a sprung-return shuttle wheel. -There's probably more, but I can't remember.
With 9-pin control, this becomes a monster tool! -I'm seriously surprised that otehr people don't use it. -If Soundmaster or Motionworks had built it into a comprehensive controller, it'd be stunning!
Summing amplifiers: I like 'em. With or without panpots, with some line-inputs for FX returns from outboard gear... for that panpots might be a worthwhile addition. -perhaps some inputs with or without, or even a modular aproach?
Keith