That can be a plus if it is sized to your needs. I guess it depends. The shape and size of the BV450 (10L) allows it to fit in my skinny 45L backpack so I am sure it would fit in many (most?) rear panniers. It would be a nice seat, great for doing laundry, and so on. I am not inclined to carry a canister on road tours, but if I were I would not consider that to be a problem for those using a traditional packing style. For bikepacking or other non pannier packing styles that may vary.

OTOH, there have been times when I wished I had an Ursak along, but wouldn't have wanted to carry my canister due to my packing style. For me the point has been moot since where I really needed bear protection there have been bear boxes, where it has been iffy I have hung food or taken other measures, and the rest or the time it wasn't a problem.