It wasn't that long ago that people were ridiculed for carrying spray. Firearms proponents were convinced that spray couldn't possibly work...Then the argument was that while maybe spray would discourage an agressive bear, but it couldn't possibley stop a full-on charge.
I don't think that time has past, at least not completely. I've been involved in a few of these threads on ETS over the years and I think that if you go through them there is at least one person implying that it you are risking your life unnecessarily by carrying spray instead of a firearm.
The other theme I've noticed are those that seem to think you aren't really defending yourself unless you kill the beast attacking you. They seem to prioritize killing the attacker over ending the attack (or at least don't see these as 2 separate things).
No, actually that is THE question and the focus of the entire discussion here. What's the title of this thread? "Bear Spray vs. Bullets", not "Does Spray Ever Work?".
Talking to this specifically, all the available information does indicate that bear spray is better than firearms for this specific use. While both can be used to successfully defend oneself against bears, bear spray both has a higher success rate in stopping attacks and a lower injury rate in their users.
The only caveat right now is that bear spray is the newer technology and therefore has fewer total reported uses than firearms. As the years march on we will get more data. However, as bear attacks are both rare and make for a good news story, we are able to see the results of the encounters as they happen. So far we are seeing the result of the studies backed up in the stories that hit the news.
It's worth noting that the article cited quoted a news story highlighting the successful use of bear spray. You would've thought that if the failure rates of spray were closer to those of firearms that they could've at least quoted a story where someone attempted to defend themselves with bear spray but failed.