It depends on the hedgehog food. Check out Reaper's post on hedgehog foods in the nutrition forum. If it's on the top half of the list, it's fine to keep feeding in a mix. If it's on the bottom half, it's not good for African Pygmy hedgehogs, and it's likely that the hedgehog will refuse to eat any more of it after being introduced to a good cat food. Make sure you do not feed any treats until after you are done introducing the hedgehog to the new cat foods, you want to be sure to catch any allergic reactions, and you don't want to stress him/her out too much by changing or introducing lots of things at once.