Flock Raiser is good stuff, but any "grower" feed would do. I have to get Dumor grower sometimes when TSC is out of the Purina stuff. Egg production doesn't seem affected by the random change in diet. If they free range any or get a portable tractor area, their "feed" is somewhat less important since it's not their only diet.
I also wish that Flock Raiser came in pellets in my area because they do seem to waste less of the pellets. The advantage of the crumbles is when you have small chicks you can just buy and store one kind of feed.