We use pure egg white albumen as our DD is GF/CF, also we put the oil in to make sure she gets some fat at lunch as well as protien and carbs.... She gets the equivalent of 1-1.5 eggs in her lunch, which is what we'd like her to have and is all she can tolerate before it tastes bad (the pure egg protien has no colours or flavours).
I like that idea... I hadn't thought of egg protein. DS seems ok with the whey, but I might try the egg. Where do you get it? (I've never seen it in the store - mind you, I've never looked for it).