I'm a Burns fan, having switched William to it a couple of years ago after I found his weight difficult to maintain on both JWB and Arden Grange Light, both of which also made him throw up small amounts of yellow bile several times a week. He's now on Burns in the morning and raw food in the evening.
9 month old Louis is also on Burns, morning and evening for him. He was on the puppy version until 6 months and then gradually switched to the adult version. Both of them get a chicken wing once or twice a week, plus various treats and usually some raw carrot every day. They thrive on it.
As it happens I'm about to switch them both to a raw diet, having read good reviews about Natural Instinct on here and talked to the company at Crufts. But that's not a reflection on Burns, simply going back to how I fed my first Cockers 23 years ago before there was such a bewildering choice of complete foods and when vets didn't almost universally try to steer you towards complete foods.