A couple more to look at besides the ULA packs:
The Six Moon Designs Starlite, with the "optional" (mandatory, IMHO) stays, will carry at least 35 lbs. comfortably. I have its discontinued "little brother," the Comet, and have carried up to 37 lbs. in it. My aged shoulders, back and hips were just fine, although my knees and feet were screaming! The Starlite has plenty of room for a bear canister the size of the large Bear Vault or the Bearikade Weekender, and will undoubtely hold a Bearikade Expedition.
I have not seen the Elemental Horizons Aquilo, but have heard/read a lot of good things about it. It got a "Highly Recommended" rating from BPL last year. If I have to replace my current pack (not yet!), I will look at its "little brother," the Kalais, which has also gotten great reviews.
Do remember that the three most important parts of a pack are fit, fit and fit!
Important: If you are planning to "lighten up," the pack replacement should be last or close to last. That's because lighter gear is generally more compact, so you don't need as much space. I can go out for 8-9 days with 40 L (2400 cubic inches) plus the outside mesh pockets, even with a bear canister. I've never had to use the extension collar on my pack and am seriously considering cutting part of it off. In other words, the pack that fits your gear now may be too big later. In the meantime, you could do some judicious trimming (aka butchery) on your current pack which could remove as much as a pound.