Alright, today I did two 1-gallon batches, one of which had two lbs of toasted buckwheat, the other two lbs of toasted GF quick oats. Both mashed with these enzymes. I mashed between 150 and 140°F for about two hours, then sparged and boiled. After boiling I had about 3/4 of a gallon of each. OG on the Buckwheat was a paltry 1.020; oats were 1.038, slightly better. I hopped each with 0.1 oz Millenium (17.4% AA) and 0.1 oz Nugget (11.3% AA), and split a pack of S-04 between the two batches. A lot of work and not a very promising result, but we'll see how they ferment out.
In the future, I think mashing a lot longer, as well as getting a finer grind on the grains, might help get better conversion. I need a grain mill if I want to continue this all-grain stuff, and probably a proper mash/lauter tun (BIABing it doesn't seem like such a great idea for a 24-hour mash).
In the meantime, I'm going to carry on with the extract-only and extract+steeping grain recipes.