last year in the dark while leading horses to water in a steep ravine, we heard a loud growling and popping, immediately the dogs were in front of us barking, my partner lit up a Sow with cubs with the spotlight right across the tiny creek from us, 15-20 yards at most, she did not flinch or act scared, she just kept growling and popping her jaws. The dogs are what got her to turn away and leave, but if that had been a big boar, or a late season hungry bear, that situation could have been much worse very quickly. Every bear is going to react differently no doubt, but I wouldnt count on a flashlight giving you much of a "deer in the headlight" type effect on a grizzly. But, its better to have a bright light, than not in my personal opinion