I think it's a good idea to swap between quality brands of food,it ensures the dog is getting everything they need.Different protein,fat,vitamin etc sources means different nutrient profiles. My motto when feeding dogs has always been 'variety,variety,variety'!
I know people who have 2 or 3 different brands of food open at the one time and swap on a daily basis,there are those that swap weekly,monthly or after each bag.
As for the dry food,my pick is Orijen,you wont find a food with a better nutrient profile than this one
http://www.zooplus.co.uk/shop/dogs/dry_dog_food/orijenHere are the first few ingredients:
De-boned chicken, chicken meal, turkey meal, russet potato, lake whitefish, chicken fat (preserved with mixed tocopherals, a natural source of vitamin E), sweet potato, whole eggs, turkey, salmon meal, salmon and anchovy oils, salmon, natural chicken flavor, sunflower oil, sun-cured alfalfa, dried brown kelp, carrots, spinach, peas, tomatoes, apples, psyllium, dulse, chicory root, licorice root, tumeric root, fenugreek, glucosamine HCl, cranberries, black currants, marigold flowers, sweet fennel, zea mays, peppermint leaf, chamomile flowers, dandelion, summer savory, rosemary extract, chondroitin sulfate, rosehips......
Oh and by the way,high protein and fat is GOOD :D However Royal Canin's levels unfortunately come from corn gluten meal,and not meat..