Update--- we just did our first batch (1/2 in meat grinder, 1/2 in food processor) and liked the meat grinder better. Everything flowed through with no issues--- just had to use the disc with smallest holes and pass everything about 4 times. With the food processor, it ground everything to an oily powder with 30-60 seconds, but then had issues with it sticking against the sides and not getting chopped in the blades. After turning it off, scraping the sides, and turning back on again, it immediately got thrown against the sides again. Maybe I should have tried a few more times, but decided just to finish off with the grinder. Its about the consistency of the peanut butter we buy fresh ground, so this was a fun experiment.
Edit—- after reading more about it, I think I didn’t have enough peanuts in the food processor. It sounds like the container should be at half capacity, so probably needed to put 2x as much in. Will try again.