I have been looking at other food I can rotate with my 2 cats Wellness core they get. However, they have to be inexpensive because I have to spend $50 on a case of wellness that only last 12 days. So I would like to get some cheaper quality ones (preferably grain free) to switch every other/every 2 days. I've been thinking of using Authority and Petguard. I brought the petguard home about a week ago (only 1 can) to let them taste and they loved it. Have any of you used either one of these foods, and if so, what was your experience with it?