I took a two day class on "surviving the grizz" last year. Looked interesting so I did it.
Day 1 - Bear behavior, avoiding conflict, covering for attack, and bear spray.
Day 2 - All Pistol.
Had a guest speaker, Todd Orr, double grizzly attack survivor. If you don't know, he's all over the internet, look him up.
Saw in person a trained captive grizzly (rescued orphan) charge at food at 35 mph. Wow was that impressive.
On both days we fired at a target coming at us at 35 mph (grizzly charging speed). From 30 yds that's less than 2.5 seconds from a dead start. First runs were with weapon already drawn and warning (ready,set,go). Second runs were draw and fire with warning, third runs draw and fire with no warning. Then with full gear on, draw and fire with no warning. It's quite different with full gear on.
A few takeaways:
It's really all about odds. There are lots of ways to get hurt, a bear is only one of them, so you have to decide just how many situations you could get into and which risks are worth the trouble to guard against in the wild.
SPRAY - Spray is virtually useless without practice. Most buyers (like me) don't understand that. I'm now surprised they even sell it without a practice can attached. They could make more money doing so. No, you don't need much practice, but you need SOME. Most people don't practice even once. If you've never unholstered spray and fired it at a charging target inside of 2.5 seconds, by surprise, you're in for, well, a surprise. You need to know what type of holster works for YOU and where you will wear it with all your gear.
Or you might be better off spraying from the hip. In our class it was about 50-50 preference for speed and accuracy on spray from hip or draw.
All that being said, spray is almost useless on a charging mother anyway. Pepper fog will not stop her. A direct hit to her eyes and nose MIGHT stop her, or it might make her more frightened and determined. Spraying a fog might work on a downwind curious hungry boar, but so will noise and human body odor.
With help from the class, I now know the odds that I could draw and spray a charging mom are almost zero. I throw spray in the backpack because it might work in camp on a calm day on a curious bear.
Claims that "spray has been proven to work" are like saying "the lottery has been proven to make people rich". True statement. Spray has also been "proven" to be useless, providing false security. You're probably better off knowing you don't have it and letting that knowledge heighten your awareness senses. If you're hiking along a noisy stream (where most trails and bears are) you will have zero awareness and that spray can would need to be on your finger the entire time.
Now, factor all of the above in, and add WIND - how many days have you hunted with no wind? Will that wind work in your favor? Can you keep her downwind while you spray?
As if the odds weren't already low, the wind factor alone ruins the whole idea of carrying holstered spray.
Also, I learned that I would only be more confused under pressure if I had both spray and a pistol holstered and ready. If you're set on bear defense, your better know ahead of time how will react, and practice ONLY that.
PISTOL - hopefully nobody needs to remind that you better be proficient drawing and firing under pressure. I venture to guess that many carriers don't practice enough to hit a moving bear in the brain under pressure. Do you practice drawing and firing kill shots at a charging target with all your gear on?
The great thing about this class was we got to try all holster types all with full gear on - chest, belly, shoulder, hip. I was about to buy a chest holster until I tried drawing and shooting while wearing a backpack and binos. Now I know I'm a hip holster guy. But everybody was different. We practiced drawing and firing three shots to the face (brain) at the 35 mph charging target. It was training but frankly it was just plain fun, too.
If you are going to shoot her, you better kill her. Bullets will not deter a mother protecting cubs - they will only confirm her fear. If you don't regularly practice drawing and shooting your pistol in full gear, you will probably make things worse, not better.
Which is more important to you? To be able to do: kill a standing broadside elk, or to be able kill a charging bear? If they are both important, do you practice both? Or do you let pistol practice suffer because it's not likely to happen? If that's how you're thinking, then just go with "not likely to need it" and leave the pistol in the truck.
Just to conclude (in case anybody's reading all this), the main takeaway is that this class did not make us experts. If anything it taught us how much we don't know. It was a lot more about making us think ahead of time, what risks are important to you, how will you react, how much preparation you need for any of these defenses. The best takeaway for me was to stop bringing holstered bear spray, and either stay proficient with my pistol or leave it in the safe.