David: I'm from Finland and visited Kungsleden only once about 10 years ago, so I might not be the correct person to give advice, but you will probably be the only person in the Kungsleden area carrying a bear canister or ursack. As far as I know, you cannot even easily buy those in whole Scandinavia. The scandinavian bears are very shy, and even more so in the reideer areas as reindeer owners generally do not like animals that are capable of eating their cattle. Ofcourse, I'm not saying that bringing the bear canister would be a dumb idea :)
However, walking between the mother bear and it's cubs is possible and some people bring bear chimes to get some peace of mind (especially when walking with a dog). Unfortunately a lot of other wildlife remains unseen at the same time because of the chime.
From time to time I've heard about rodents trying to get to peoples food, mostly near the huts, but even that is not so common thing to happen.