Thought I'd jump in here. I've recently been forced to let my hens full time free range:
They've done exceptionally well, and my feed bill has basically gone down to zero. The only reason it's not is because I insist on offering them some feed every day, apparently because I like watching them leave it on the ground and waste it.
I just finished demolishing the old coop, and I will be building the new coop with free ranging in mind. It will still have a pen, as I have two chicken eating dogs, so I need to be able to separate the creatures. I tested them with my one non-chicken eater, and they really don't try hard to get away from him. Boo. Oh well.
My one other worry was hawks, but we have witnessed them successfully take cover from one overhead. Yay!
So once the coop is built, I will be penning them up for a few days to get them laying in the house again (I can't for the life of me find my leghorn's nest). And then my plan is to shut them in at bed time, and then let them out after the dogs have been put up after morning chores. I'm pretty pleased with how the new set up will run!
Waiting on the new coop to be built: