I figure that since I own a Garcia and a BV450, if I were to buy an Ursak it would probably be only for backpacking and bike touting where 5 day capacity is enough for me these days. I am willing to carry about that much and on tours I don't need to carry that much. So the 10 liter Ursak is probably fine for my usage. On canoe trips I can take either or both canisters and any Ursak I might buy. All together that would be quite a bit of capacity.

BTW, the reason I have two is because I originally bought the Garcia and later decided it was preferable to have a smaller canister. It has been handy to let friends and family use one on group trips.