I feel your pain....my base weight is probably 10-10.5 lbs with the pocket camera and extra batteries I have.
Canisters sucks, but you need one.
I do agree that a Bearikade Weekender would be a good choice for you to simply have for the Trips in the Sierras.
Problem is that a JMT trip is uniquely long and buying a canister just for the trip probably does not make sense, unless you anticipate taking long trips that would require 7 plus days of food.
Would not count on the UR Sack.
My friend, Jeremy, had another trip where a bear really damaged the UR Sack and turned his food to dust...basically lost food.
No longer an option for him as he has lost confidence in the UR Sack.
To be fair, the bag did not get ripped apart, but was damaged with some holes in it.
He DID NOT have the metal liner as an option, which might have helped.
10 oz is a big difference, but I don't think you can easily get 7 plus days of food into a Weekender.
Tough choices, but that said....JMT is a trip of a life time and any amount of money you spend will be worth it so you can enjoy the experience and views.
Fortunatley, backpacking is cheap vs. taking a vacation with planes and hotels....so cost is relative.