I agree with you that 4 Health is high in potato and peas, and definitely not limited ingredient, but it is kind of a middle ground with what you are currently feeding. Fish meal is in a lot of foods now, so fish is only novel if your dog has neve been exposed to any form of it. To me, the bigger concern about fish is the number of containments it has. After you get Atlas onto another food, then try other proteins.
A lot of people have good success with ProPlan and that is why I am considering it. The Focus Sensitive Skin and Stomach (I think that is the one you are referring to) is basically fish and grains, so it is more of a limited ingredient food than 4 Health. You are correct, it has prebiotics and no probiotics. If you go with ProPlan buy a probiotic to supplement with. I prefer the ones that come in powder form rather than capsules.
