Bear-Resistant canister approvals are a mess as each National Park set’s it’s own list not to mention National Forests and other public lands. Sometimes it makes little sense to me as well for example I don’t believe the Bearikade is approved in Rocky Mountain National Park where they just have black bears, but it is approved for Wrangell St. Elias NP where they have both black and brown bears.
The UrSack will never be approved in SEKI if you frequent the Sierra. It get’s political with the SIBBG (Sierra Interagency Black Bear Group) who was a testing organization of bear canisters made up partially of rangers from SEKI was sued by UrSack for not approving their design (despite reportedly passing the tests) and that lawsuit forced SIBBG to disband. The UrSack later got IGBC (Interagency Grizzly Bear Committee) approval, which is often used as a blanket approval in many parks but not all.
Despite the UrSack getting IGBC approval it isn’t hard to see SIBBG’s concerns that it is a much more error likely than a hard sided canister. I have an UrSack as well as a Bearikade and Bear Vault and admittedly I have much less confidence in the UrSack to protect my food than either of the hard sided canisters. I use it in areas where an IBGC canister is required, but I don’t expect to actually come into contact with any bears (i.e. I will be away from high traffic areas and staying in off trail high alpine camps where bears could be, but there is a low probability of one coming around my camp). If I am going to be camping lower or in higher traffic areas then I use a hard canister.
I’ve been backpacking in canister required bear country for a decade and only last year had an event where a bear touched my canister (that I know of). I was doing the Southern Sierra High Route and camped one night on the JMT (mistake). A bear silently came into camp and turned my canister over, apparently rolled it around a bit, and bit my fuel bottle that was sitting beside, but not inside (mistake) the canister.
If you are looking for a canister that is good everywhere then the BearVault is as good as it gets. I think it’s allowed everywhere except for a small area in NY where a now deceased bear named Yellow-Yellow learned how to open them. I dislike the Bear Vault for a couple of reasons, but it is fairly inexpensive, has a wide opening, and is approved nearly everywhere. That being said I use a Bearikade when I can as I prefer it to the Bear Vault, but there are a lot of places it isn’t approved.