When Raelin was a pup, I took her out on a nice secluded trail, and took her off leash. She is a confident dog, and has no toubles wandering away from me, and she did not take off, but she did find something very stinky to roll around in!!
I have taken her off leash a few times, but the other problem is that there are a lot of people out there that are not dog people. It is not fair to them to be approached by a strange dog, the public trail is there for all to enjoy! JMHO.
I have now found that it is safer for her, and easier for me if she stays on a lead. She still gets her exercise, we both have a good time, and I feel better knowing that she is safe.