I have a friend who's brother in law used one on a CA backpack trip for the very same reason.
Black Bear found where he stashed the sack and tried to get into it. Bear didn't open the bag, but everything inside was mashed up like if you took a bag of M & M"s and rolled it between your palms.

In his case they yelled and threw rocks and bear ran off. The literature said to tie to solid branch at least 5" in diameter so bear can't gnaw off branch. That was harder than you might think, finding a suitable branch that thick and still low enough to reach from ground and tie that specific knot the want you to use. He also said that branch had been gnawed on to the point if they hadn't chased the bear off, it might of broken and then what do you do, chase the bear thru the woods?

Bottom line they liked the strengths/weight of bag, but next time will bring some strong cord and hang bag from a high limb out from the trunk like in the old days.

I've seen other bear sacks that instead of tying to a 5" limb or bigger, they used a cable to secure to a tree trunk.
If you rather not hang a bear sack, but think like I do that finding, that perfect limb MIGHT be a problem, I think quick trip to the hardware store could fix that "potential" problem.

Buy about 4-5 ft of that steel cable with the nylon coating, the type you see on garage doors.
It's plenty strong. Have the hardware double crimp loops on each end. Then find a locking type of carabineer, maybe for hardware or sporting good store.
Loop around tree, secure with carabineer and then tie sack off as directed. I think it would be just a secure and easier to deploy just about anywhere you have trees.

Well I have pulled the trigger on the Ursak (of course I did). My thinking is even if a bear did paw and gnash his teeth on the thing it is hard to hurt oatmeal and other sundry dried goods such as Mountain houses granola w/blueberries and milk.

What I do know is that if a bear finds your oats w/raisins and your granola there won't be even one flake left (thanks Mr Sawbill Lake bear). So let him gnaw on the bag for a while, won't hurt much.

And thats if he even finds it.........I pack my oats in a Nalgene wide mouth flexible bag "canteen" (96oz) which is the perfect camping food bag and completely airtight which strongly reduces odors.

I may have to give ST's steel cable suggestion some thought. Thank you for weighing in........ Might not be any trees to tie to where I'm going.........just a bunch of rock. Marmots might be a bigger nuisance than bears!