I have both the BV 450 and 500 and have used both on the JMT. I also have an Ursack. The BV 450 will hold 440 cubic inches and weighs 33 oz and the 500 will hold 700 ci. and weighs 41 oz.

On my 2008 JMT hike, I used the BV 500. For most of the hike it had more capacity than I needed and I carried a half pound more canister than necessary. When I re supplied for ten days at MTR, I was able to cram all but about 1 1/2 days of food into the BV; the rest went into my Ursack; included in the MTR re supply bucket. I, obviously, used the food in the Ursack first.

Last year, I used the smaller, lighter, BV 450 and again, carried the 4 1/2 days of MTR overflow in the Ursack. Canisters are not required south of MTR until you reach the Rae Lakes: hanging or Ursack protection is acceptable between MTR and Rae Lakes.

I plan to do the same thing for my JMT hike this July. I have, however, been giving some thought to buying a Bearicade Weekender. It is a bit lighter than the BV 450 and holds 650 cu. ins. They also have a good resale value when no longer needed. It would cut down on the food volume in the Ursack coming out of MTR. You can rent the Weekender from wild-ideas.net/