
Salmon based food tends to be my go-to for a semi elimination diet, when I've got a fair idea of what the triggers might be. I haven't yet had a dog be allergic to it and I've had several dogs with food allergies.
The problem with using any kibble for this purpose is that there are multiple ingredients, so unless you've already got some idea of what's going on, it's fumbling in the dark. In those two varieties of canagan you've got potato, sweet potato and peas so if any of those is a trigger, changing foods won't make any difference, however long it's fed for. But if the chicken is the issue (and it is a common trigger) then it'll work beautifully! That's the problem.
Either a raw, single novel protein diet or home cooked single novel protein and single novel carb diet tend to be the best ways to do an elimination diet. You know exactly what's going in, and because the dog has never had them, he's unlikely to react to them. So you feed until the reactions have eased (6-8 weeks is the typical time frame for this stage), then start adding things back in one at a time to look for reactions.