I'm feeding Fromm Adult Gold (Wisconsin duck) and was advised by the breeder not to go grain free until he was a year old. I am not sure why.
I made the mistake in the early 80's of feeding a protein rich food to a growing large breed dog, who developed OCD in his shoulder. We did the cartlidge flap surgery, however he still had debilitating arthritis in that shoulder.
My adult dogs are on Orijen and Taste of the Wild, with a variety of flavors.