I went with the gear driven JSP because two of the other mills I have had would periodically just sit there and spin the driven roller while the passive roller did nothing. I'd bang on them, stick stuff down into the hopper to try to force some grain into the teeth of the rollers, etc. Very frustrating. And yes I tried various gap settings.
Like I said in a previous post, the JSP just chews through the grain. I turn it on, load the hopper and come back when it is done.
Here is how I have it set up:
I got the cabinet from the local ReStore (Habitat for Humanity's 2nd hand store) for ~$10, put wheels on it, had a friend build the top so that the shaft from the motor would match that of the mill, and then wired a light switch to turn it on and off. Voila! I just stick a grain bucket in the door under a custom grain chute (a leg from a pair of chest waders). BTW Thanks to AmandaK for the sourcing the motor (from https://www.allamericanaleworks.com/