I just thought the mention that if going for a canister was what someone wanted to do, I'd consider the BV425. It is pretty small at 5 liters, 8.7 x 6 inches, and 1 lb. 12 oz., but for on pavement touring most of us can shop every day (or two). If you shop you can leave that day of food out because you eat it before camping. So I could jam another 2 days of food in if I choose compact food. For about $75 or a bit more it is pretty cheap. I still don't plan to start carrying a canister for touring and have a BV450 so I may not buy a BV425 for backpacking, but if I were doing a lot of overnight or two day backpacking trips I would.

If you can't get by with the BV425 the BV450 might be for you. I have managed with the 450 for 4-5 days when backpacking (the first day carried outside of the canister).