Seem to some people as if they are overreacting, but its the noise your neighbors are not used to (sibes sound different than other dogs).
I know of many who tried the invisible fence, shock collars, etc, sibes learn very fast that if they take off at full speed they can get beyond the 200 yard range of the "stimulation" control in a few seconds at most. Usually the shock sends them faster which teaches them to outrun the range very quickly. Think about it, you are walking around, suddenly you recieve a shock, you panic and run as your instinct tells you to do, as you are running you are being shocked, so you are now at full speed, in a few seconds the shock stops. A positive result from your reaction to run away, therefore you know from the first experience, run like heck and be out of range, the pain stops faster than sticking around.
I know some sibes that it worked the first time, then they prodded at the borders, and wore the battery down in no time at all, the shock becomes weak. Now they give you a smile and run away, smart dogs. Their skin and fur protected them enough to put up with the shocks in short bursts, even turned all the way up, they killed the battery and ran away.
I can see trying it to reinforce a trained dog, but not using it as a training tool. Think in these terms, your voice calling them back when they get shocked, they now learn to fear the sound of you calling them back, and run away faster, and scared.
If I was repairing a fence, Id use a cable, and supervision. Mine are never outdoors unsupervised.
I just read an article on this website talking about people leaving unsupervised dogs, and cats in fenced yards, the result with some small dogs and puppies is local predators taking advantage, it mentioned specifically that a 6ft fence wont stop coyotes and bobcats at all.