This might just be rural legend, but a woman I met who worked at the glacier national park general store told me that it was very common for an english-as-a-second-language family (usually Japanese) to purchase bear spray for their trip into the park. Unfortunately the brand they sold was labeled "bear repellent spray", and came in a can of similar size and shape to the ubiquitous insect repellent spray which is a staple of the north west.
The following scenario supposedly played out about twice a year, more often if she was lucky: Being unclear on the concept, and able to read just enough english to make the next logical mistake, some well meaning parent would line his or her children up in the general store parking lot and, yup, spray them with bear repellent
I can't guarantee that it's true, but I can sure see it happening. What sort of negligent parent would allow their children to go into the park without a protective layer of bear repellent on them?
Anywho, I use this stuff every day and I agree that if a can of bear spray ruptures (not just leaks) in flight there is really zero chance of being able to control the airplane. If anyone has any question about this, get a little jogger size can (about 1/20 the volume of a can of bear spray) and spray it on the ceiling of a friends car, then see how long you can last inside. I won't even allow the human-size cans in my plane, though I've never had one leak.
I must say that I still like the idea of a piece of aluminum irrigation pipe capped at both ends...I guess plastic pipe would probably be strong enough as well.
As far as how well it works on bears...for most people it's probably a whole lot better than a firearm. I'm a gun person, but I'd rather spray a charging bear with OC than try to deploy a marginal weapon like a .44 handgun. I think the OC has a better chance of stopping the bear from continuing the attack. Given the choice I carry a shotgun with slugs, but if I don't have something that powerful my first choice is OC spray.
At the end of the day it shouldn't matter. Anyone who is willing to study bear behaver and modify their own behaver when in bear country has a very small chance of ever having an encounter. As Doug Peacock was fond of saying, anyone who can't find the bear before the bear finds them deserves to be taken out of the gene pool (not a direct quote, but the same message).
In all but the most remote parts of the earth you are far better arming yourself agains two-legged predators and letting the four-legged predators worry about themselves. Besides, three weeks after you die of prostate cancer your name will be forgotten. But if you get killed by a rampaging grizzly your name will live on wherever people gather to drink.
