My chickens have been successfully free ranging for a year and a half but our 10 acre property has natural hillside borders or woods on all sides which conveniently keeps them at home on the 2+ acre patch surrounding our home.
I think the ability to free range depends solely on your topography or your willingness to build a few perimeter fences where dangers (such as a road) or neighbors come into play.
It's different for everyone. Also, please take into account your predators (whether they be raccoons, possums and especially the neighbors wandering dogs!). Constant vigilance is necessary for free ranging birds.
It doesn't guarantee that you'll not have losses but it will severely reduce the chances. If there are wandering dogs, then you may have ethical issues. Personally, I wouldn't think that I'd shoot a neighbors dog over a chicken which doesn't cost much to replace but I understand why others would, especially when the dogs are repeat offenders and the neighbors are unwilling to take responsibility.
I think neighborhood dogs are the #1 variable to consider for free ranging chickens.
That said, I have a game cam mounted with constant surveillance on the coop area and whenever predators show up, I take care of them lickety split.