This was a "quick and dirty with what we have on hand" project.
I had plenty of Vex encoders on hand.
My first idea was to attach some retro-reflective tape to the output, and use a banner sensor to count pulses. This would have been the zero-effort approach, and I think they decided it wouldn't annoy me enough, so they wouldn't let me do it.
During this project I relearned to hate the FP gearbox (specifically the grease they use inside it).
JV