I use a gap of 0.034" on my MM2, and I brew in the Foundry 10.5 using both the grain basket and a bag, along with semi-regular stirring of the mash in addition to recirculation. I have a set of feeler gauges that I use to set the gap, and I check it before every use of the mill.
If I'm doing an "average" gravity beer I'll get around 68% "mash efficiency" (as reported by BeerSmith) with a typical 60 minute mash at 152 followed by rise to 168 for 10 minutes. I can bump up the efficiency by mashing a touch longer or doing a sparge with a half-gallon or full gallon of hot water (the latter is something I usually do for high gravity beers). So, I've been hitting 73 to 75% efficiency pretty regularly, and I'm satisfied with that.
With over a year on my Foundry now, I know the behavior of my system pretty well. So, I can adjust recipes and process to hit the results I want pretty consistently, which is a nice feeling!