We feed our flock Scratch & Peck too, and they love it! It looks and smells great, and the hens don't waste a crumb of it. Whatever spills onto the floor gets cleaned up in no time. We briefly switched to an organic pellet (we were about to go on a long trip and the store that carries the Scratch & Peck is less convenient, so we had to make a last minute temporary switch) and the difference was noticeable - the chickens hated it. They lost weight, egg production went down, and there was so much wasted on the floor of the coop. We're back to Scratch & Pack, no exceptions!
We avoid soy and GMO's like the plague, and for awhile I was getting the corn-free soy-free feed (I'm allergic to corn) but now we get the one with corn (but no soy), and it hasn't been a problem for me. Over winter I wanted them to have the extra fuel from the corn, but will just stick with it year round now.