GF All Grain Results?

I'm considering buying placing an order with Colorado Malting Co., who say they currently have White Millet, Red Millet, Buckwheat, Amaranth, and Teff, all malted. I'm not really sure where to start, though - does anybody have experience brewing with these grains?

I've heard that White Millet is probably the best base grain, especially if you roast it first. Is this accurate? What kind of efficiencies do folks typically get? I'm planning on doing 3-gallon BIAB batches.

I ordered 5 pounds of a few different GF grains from them but they havent come yet. I was just planning on doing a variety of small test batches to see what kind of conversion I can get from each, then what happens if I add in enzymes or other things. I would say just order something up and experiment with it