Ranchers have been using portable electric fences for decades to contain sheep and other livestock, and to deter bears and coyotes. Those products are just as good as the "bear fences" and half the cost. They are a good deterrent for all manor of critters from bears to skunks. The "bear fences" are sold to touristas. Here's a link to what I'm talking about:
http://www.premier1supplies.com/fencing.php?mode=detail&fence_id=40
I've had many encounters with both black bears and a few with griz. I was even awakened one night by a blacky sniffing my head. Sleeping in a raised RRT is far safer than being on the ground for the simple reason that it gives you precious seconds to react. A ground attack will most likely find you in a flattened tent with the bear on you before you know anything is wrong.
Noise can be a deterrent to a casual bear encounter, but a serious encounter won't be averted so easily. When I'm on foot I carry a titanium framed 357 mag. At camp I also have a short barreled shotgun that is never beyond reach. A handgun of any kind is a very low percentage option though! Stopping a charging bear with ANY handgun requires a brain shot and that is akin to drawing and hitting a tennis ball bouncing toward you while reeling from a massive dose of adrenalin. This is one reason that spray is often a better option. A handgun could be used to stop a mauling though since that would be at point blank range. Many of the encounters I have had have been with little warning. Bears are amazingly stealthy. Nothing that you carry will be of any use if it is not accessable. One of the spray companies sells a chest harness to keep the spray where you can reach it if mauled.
Bears will attempt to get into just about anything for food, but any bear that attempts to enter your tent at night is doing it for the purpose of a predatory attack. Your only option is to fight with deadly force.
Most people assume that black bears are harmless. In general I would say that raccoons are a bigger threat, however, the only serious encounter I have had with a bear was with a black bear. The stand off lasted several minutes with the bear posturing and circling me. Yelling and throwing rocks did nothing to drive him off. Eventually he turned and walked back into the woods. That type of behavior is well documented with young male bears, and they are essentially sizing you up for a predatory attack. I assume that bear was a young male. As long as I stood my ground he gave me a 20 -25 foot perimeter. That's why I didn't shoot him, and eventually we had a better outcome. Grizzlies though require different rules of engagement.
I think the bell idea is a cruel joke. Awareness is the key, and you cannot be vigilant with that racket going on. Bells are fine for fools on a fools errand. Their safety is in the hands of fate anyway.
Regarding firearms, I always carry them regardless of restrictions or bans such as in Yellowstone. They can kiss my lily white behind.
Most of my travels have been and continue to be with dogs. They are very well trained and a great asset in the back country. More than once they have awakened me in the dead of night with a low rumble in the chest. They only bark when I say "who is it?". Otherwise they are quiet.
I have seen wolves in the wild twice, but both times they were gone in a few seconds.
