Yikes. That surprises me a little. The Arc'Teryx Bora ($375) is a well-made pack. But you're doing big trips and carrying big loads, so I guess it's possible the pack was just over-matched.
My short list for a replacement would start with the Gregory Denali Pro ($499). This pack has been around for some time and is essentially unchanged since 2003, aside from minor tweaks to color and suspension. A great pack. A great BIG pack, with 6,400 cubic inches of capacity. Excellent suspension, good design for organization, lots of external tie-downs.
You might also check out the Granite Gear Stratus Access FZ 5500 ($390). As the name implies, Granite Gear is determined to make stuff that is tough. And the Access is, without adding so much weight that just carrying the pack becomes a chore. The FZ 5500 is a bit smaller than the Gregory, but still has an ample 5,500 cubic inches of capacity. Which should be plenty. I know food still takes up a lot of space on long trips, but the rest of your gear (tent, sleeping bag, etc.) is likely more compact than it was when you started these trips.
Third choice: Osprey's Argon 110 ($419). This is even larger than the Gregory, with 6,700 cubic inches. I really like the way Osprey designs a pack for storing stuff, and the Argon is no exception. Easy to pack, and easy to put stuff you need where you can find it. Excellent suspension, including a hip belt that can be custom molded. Very nice pack.
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