William, castrated male, has been on Burns for about 1 year now and it suits him far better than Arden Grange or JWB did. He tended to put weight on with those and also to throw up a bit of horrid yellow bile most mornings. That hasn't happened since he's been on Burns. His Retriever friend Ruby, who gets colitis and cystitis and puts weight on easily, also does well on Burns.
I think if you read other threads on here you'll find fans of all the above 3 foods, but some COLers have found that their Cockers get skinny on Burns. It's great for William but he's a bit of a couch potato around the house, although energetic on walks and when we do agility.