I can completely relate to this question. I was very concerned about letting my chickens free range because of predators (including my own dog).
I decided their happiness overruled my own fears so I trained them to come when I call them "chick, chick, chick" by giving them some special food. I did that for a couple of weeks in their run.
The first thing I do is lock our dog up in the garage and let the family know he has to stay there until the chickens are put away for the night.
Then, the first time we let them free range I was out by their coop shearing llamas so we let them out since I could keep an eye on them. It was about 7:00 p.m. so I knew that they wouldn't be out real long also since they would want to go in at dusk.
Watching their joy (you could just see how excited they were) was so great we didn't get the llamas all done ... had to stand there watching the chickens!
They stayed pretty close to the door of the pen that first time.
At this point I only let mine out in the evening (around 6:00 to 7:00) and I do walk to the window, or sit outside if I have the chance, to watch them. My kids also like to be out there with them so I feel better. I've watched all my barn kitties give way to them (the chickens have rushed the cats and sent several of them running away) so I feel fairly confident that they won't attack. They put themselves away every night about 8:30 now (it's gets earlier as the sun goes down sooner) and we just go out, count to make sure everyone is there and lock em in for the night.
I will be heartbroken if we lose any to predators and I do realize that it is possible that we will. But, I won't let them out all day and we keep an eye on them, somewhat, when they are out so I'm hoping that we won't go through that grief. Just watching how excited they get when I come to let them out is worth taking the risk for us. Also, we do have a Rooster that keeps a very close eye on his girls so I hope that helps.
I personally would suggest that you give it a try, under your watchful eye (even if you can only let them out for a half an hour a couple of days a week) just to give them the chance to really be chickens. But, only you can decide if your situation will work. If it doesn't, don't worry about it and just love them where they are -- and give them some special treats more often.
Good luck deciding what to do.