Have you ever tried substituting in any other flours such as whole wheat or barley?

I have not made this recipe, but I routinely substitute whole wheat flour in everything I bake. For cakes, I use 50% whole wheat flour, sifted to remove the bran. For muffins and other quick breads, I use 100% whole wheat flour, unsifted. For yeast breads, I use 100% whole wheat flour, unsifted, substituting 2 tablespoons of gluten flour for 2 TB whole wheat flour for each 3-4 cups called for in a recipe. I don't have any experience with barley flour. White flour products taste so blah after you get used to whole wheat.

I never have Megan but maybe others will chime in...