Having been through a few bear safety classes for my various jobs here in AK, this is what I can share.
What ever defensive system you select, make sure you can deploy it in 1.5 seconds or less. If your bear spray is in a pocket on your pack, it will take several seconds to dig it out. If your shotgun is strapped to your pack it will take several seconds to get it off and use it. If you carry your defensive system in such a manner that you can't get it in operation (armed, safety off, and aimed) in 1.5 seconds or less rethink your system and how you carry it.
Learn how to acquire your sites for close quarters battle. You have to be able to aim your weapon quickly. Aiming requires two points of reference. Having a large front site on a pistol helps speed up this process. Peep sights on a long arm help speed this up. With peep sights on a long arm you want a bright dot for the front and a large aperture for the rear. However, even rifle sites like the ones on a deer slayer slug barrel will work better than just the front bead on a short shotgun barrel. You cannot aim with only one point of reference on a long arm.
If you are using a pistol, you have to practice drawing the weapon and acquiring the front site on target. I have a big dot site system for my Redhawk from
24/7XS. For CQB shooting its the cat's ass. I struggled for years with the factory hunting/target sites on the Redhawk and quick shooting. The big dot sights changed the situation from a "I don't think this is possible." to a "this is the easiest thing I've ever done." It was as if the gun was aiming its self. I know its not, but once you know how to shoot a pistol the big dot system makes it seriously easy...and fast...stoopid fast. And if you decide to use a pistol, you need a few thousand rounds of practice to burn the sight picture in to your mind. I took a pistol marksmanship class in college decades ago. That target shooting and all the other stuff in my lifestyle helped me understand what I can and can't do with a pistol.
For a shotgun you have to figure out how to make, and keep, it tactical ready that is also safe. For my 870, I empty the mag tube and chamber. Charge the weapon, then pull the trigger on the empty chamber. This releases the bolt lock system. Load the mag tube and leave the chamber empty. Now all I have to do is stroke it and pull the trigger. I learned this in a classroom setting and thought it was kinda stoopid. However, out on the range I was able to pick the weapon up off a table, stroke it, aim it, and put two rounds into a 6" circle at 15 yards in under 2 seconds. Having handled shotguns, specifically 870's, for decades helped. Being forced as a child to learn how to shoot with open iron sights also helped. If you are of the modern age and have only used optical sights you are at a disadvantage. There are expensive solutions though.
You also need to practice with live ammo on a moving target. I have only had one class that provided that. One of the funnest days on the range ever. One of the scariest as well. A bear target on a wheeled cart being pulled towards you by an ATV behind you at even 15mph is enough to jack you up. Almost like the real thing. When you are jacked up safety issues come along. Lots of extra work has to go into setting up the range to be safe. But its so much fun. And you will quickly learn what you are and are not capable of.
Do not use a shotgun with a pistol grip. You can't aim the weapon well and you can't control the site picture very well under recoil. It will slow you down on the second shot. And unless you have really strong wrists you probably won't get a second aimed shot off in less than 2 seconds.
For all your firearms they need to be tuned to remove faults caused by design or machining. I have had 870's fall apart due to the poor build at the factory. New Redhawks have a sear spring issue I am told. You want stuff to work when it needs to work.