I'm using from a local mill now (my flock is in the sig below, its significant, so are my feed costs), but when I started, it was about a dozen birds at a time, in batches. I was very satisfied with both the Purina and the Nutrena products, and would likely continue to use their "All Flock/Flock Raiser" offerings if I could ensure freshness at my local
TSC and cost wasn't a factor.
Some people swear by Scratch & Peck.
I don't put a premium on Organic, so I'm not one of them. If you do, and its worth tripling or quadrupling your price per pound (or you plan to raise and sell organic birds), Scratch & Peck is one of the more available brands.
OTOH, if you troll the boards here, or use the search engine, you will find a number of posters have had problems with whole grain feeds generally, not just the Scratch & Peck brand. Why??? Because chickens are like picky teenagers - given the choice, they will pick out their favorite grains and leave the rest, resulting in diet imbalances.
So, no, I don't think the cost is a benefit.