If you keep their brooder dry, (I used a thick layer of pine shavings) they will eventually eat the food they threw all over the place and they'll enjoy doing it. You just have to pay attention and not refill the dish until they've cleaned it up. Make sure you raise up the feeder and water dish as high as you can where everyone can still reach and the water won't get spilled/trampled so much, making the bedding soppy.
As far as soy and corn free, the only advantage I really see with those feeds are for people with allergies and can't handle the food. A lot of research went into chicken feed to make it a complete and cost effective diet. I don't see Scratch and Peck feeds as any more natural because a Chicken's natural diet doesn't consist of mostly grains. The rest of the nutrition relies on a protein, vitamin and mineral powder that can easily get wasted. The manufacturer of the feed recommends fermenting to keep it together but their vendor who supplies the powder doesn't agree. (There was a thread discussing it here on BYC with reps from SnP adding commentary. If I had the time I'd dig it up.) Anyway, I find the official regulatory definition of "Organic" as a farce, so I don't bother seeking it out or paying more.