Gluten-free Flour Mix

I try to go as whole grain as possible when I bake with gf flours. Usually I use 100% whole grain, but sometimes I will add a starch depending on what I am baking and for whom I am baking. I usually use glutinous rice flour when I am baking for Ben, potato starch if I am baking for Sarah, or tapioca if they are both going to eat the end product. I like to use a mixture of brown rice, sorghum, millet, buckwheat, and sometimes amaranth. The buckwheat I like to use is hulled so my flour isn't flecked with black bits from the hull. I have a trusty grinder and grind at least twice a week (I make probably 6 loaves of bread a week, some from Pamela's bread mix and some from my own recipe). Brown rice is hard on the grinder and I fear mine is about the die, but I will definitely buy another when it does. As it is, I try to grind brown rice in smaller batches.
Here is my basic proportion:
1 part brown rice
1 part sorghum
1/2 part millet and buckwheat each
If I have amaranth I throw it in the hopper with the other grain.
I store the grain in my favorite glass container - it fits a cup measure easily through the mouth - in my pantry.
I like to add some flax as I am mixing a recipe together because I think flax should be refrigerated.