Well, so far so good. I've been mixing a small amount of the Blue Wilderness in with her EVO and she's been doing great! Before if I even mixed a small amount of another food the runny poopies returned.
Blue Wilderness is made by Blue Buffalo, which, AFAIK, is a great food. Mine were on Blue Buffalo dry and Solid Gold wet but it did not agree with the new guy no matter what. They have both been transitioned to Canidae and so far so good.