Billy, I mix all sorts together. I have tried to feed both ends of a grow out (BG) with primarily Optimal BG and Purina AM 500 and I can't say I can visually see anything different but I have seen them spit a pellet back out if used to having something else.
Lusk swears by the Purina growing giant BG but I've got some good ones feeding on optimal bass pellets and they don't want anything smaller.