Hey Brian,
We plan on using an off the shelf motor, and then adding a second front bearing to it to make it robust to axial loads. It should be possible to use a wide variety of motors without having to have an adapter for each one.
Right now we are focusing one specific gearset. We can make others if the need arises, but we'd prefer to have things working with a single gearset, and then change the motor kv if the power output needs to be adjusted.
Brenner ...