Interested to find out if the mill setting makes a difference? We've done our own experiments as well and coupled with many BIAB brewers comments from around the web, come to the same conclusion - a finer crush aids in faster more complete conversion, higher efficiency numbers, and in our humble limited opinion a better tasting beer - but we're a bit biased on the taste side of things.
The folks at Brulosophy conducted a test that you can find here.
John Palmer says that the grist size has very little affect on efficiency rates, on average 1% for all grain brews. I’m curious as to what the actual data show for BIAB.