A lot of good info in this thread. Here in the northernmost chunk of Idaho, there is a healthy population of grizzlies. I hunt blackies in the section of the unit that has the densest population of grizz. It always amazes me how they go out of their way to avoid humans. If you give them enough warning, you will probably never even know they were there!
Having said that, I always make sure my head is out of my ass while in grizz country. I look at potential camp sites for any bear sign and previous human sign. Bears will return to a popular camp site for years if people are careless with their food and garbage. I never leave food in a tent or pack and always clean up as well as possible after eating.
As far as defense against a charging bear, I've always been wary of folks I've taken with me who are packing some version of the latest biggest magnum. I'm sure there are folks who are talented with them, but most of us aren't

I have a friend who studies bears at WSU. I have watched 400 pound grizzlies fight over apples thrown over the fence to them. Their speed is hard to describe to somebody who has never seen them run! I suspect that from 10 yards or closer, your brain probably wouldn't be able to tell your hand to draw...I think it would be way better to do everything possible to avoid the encounter rather than think it can be controlled with a weapon of any sort.
USFWS biologists were snaring grizzlies in the drainage I was scouting last year. I went into the snare sites with them a couple of times. They swear by bear spray. That's all they were packing when doing random checks. When they caught one, one of them had the dart gun while the other one kept a Rem 870 with slugs on the bear. One morning, they heard a cub bawling on a set. They gathered up as many warm bodies as possible to swarm the site in case the sow was around. Turned out it was the sow who was caught and her 2 yearling cubs wouldn't leave. They said a sow will rarely defend a yearling when faced with 4 to 5 guys coming in, but can get very nasty when she has newborns! The point being that there is strength in numbers, but avoid sows with little ones at all costs.
If you see one at a distance and want to avoid it, give it a wide berth with the wind at your back and make enough noise to let it know you are there but not so much it thinks you are a threat. Bears are like dogs with their body language and hierarchy. Give it plenty of opportunity to hit the flight button instead of the fight switch!