If you're making a small amount to test with, it might be worth making a batch of each and see how they go over. I don't think a small amount would be harmful either way. I've offered small amounts of leftover hornworm food to my roaches and they seemed to like it. It gels up nicely when mixed with boiling water and left to set. Here are the ingredients (from Repashy's site) in case anything stands out as a possible substitute to try out for binding.
INGREDIENTS: Soy Flour, Stabilized Rice Bran, Corn Meal, Cellulose, Calcium Carbonate, Brewer’s Dried Yeast, Cane Molasses, Dried Seaweed Meal, Lecithin, Locust Bean Gum, Soy Phytosterols, Dried Kelp, Dried Watermelon, Rose Hips, Hibiscus Flower, Marigold Flower, Paprika, Turmeric, Citric Acid, Potassium Citrate, Salt, Calcium Propionate, Methylparaben and Potassium Sorbate (as preservatives), Magnesium Amino Acid Chelate, Zinc Methionine Hydroxy Analogue Chelate, Manganese Methionine Hydroxy Analogue Chelate, Copper Methionine Hydroxy Analogue Chelate. Vitamins: (Vitamin A Supplement, Vitamin D3 Supplement, Calcium L-Ascorbyl-2-Monophosphate, Vitamin E Supplement, Niacin, Beta Carotene, Pantothenic Acid, Riboflavin, Pyridoxine Hydrochloride, Thiamine Mononitrate, Folic Acid, Biotin, Vitamin B-12 Supplement, Menadione Sodium Bisulfite Complex).