On a long trip, where you won't be passing resupply points, would the "backup" value of two smaller canisters instead of one larger canister justify the extra 2 or 3 ounces? When I'm planning to spend a week at Isle Royale, where I'll be walking away from the only store and won't swing back by it until the end of the trip, I take 2 small canisters instead of a medium. My thinking is that, if I mess up the threads or jam the valve on one canister, I can still get at half my fuel.