For the base weight you have, you certainly don't need a really heavy pack like the Bora! It's fine if you're carrying expedition=type (60 lb.+ loads), but it's definitely overkill for what you have. On the other hand, it definitely sounds as thought your Kelty isn't doing its job. Packs are like shoes--the fit depends very much on the individual. With the base weight you have, you might want to try other packs in the 2-3.5 lb. range, like the Granite Gear packs or REI's so-called "UL" pack which definitely isn't UL, but which (in women's sizes) I found quite comfortable. (I didn't get it because I found a lighter and more comfortable pack online, but it was #3 on my list after lots of research.) If it works for you, the REI UL60 (~3.5 lbs.) (it has a new name which I've forgotten) is relatively low-priced and often on sale. Take your gear to the store with you (to be sure it will fit into the pack), load up each pack you're considering and spend some time walking around the store. Once you've bought a new pack, take some long hikes close to home--even if just several hours on the sidewalks in your neighborhood--to be sure the pack works for you. Return it if it doesn't! If you don't mind paying return postage if they don't work out, try the ULA Catalyst or the Six Moon Designs Starlight or Comet (with the optional stays). Don't do this until you've tried a bunch of packs in the store, fully loaded with your gear and fitted/adjusted by a competent clerk (not all clerks are competent, even in REI--if Bearpaw from this site worked in my local REI, I would be a lot more comfortable about shopping there!). Then you'll at least know what a properly fitted and comfortable pack feels like! What you really want is something that feels like the Bora but weighs half as much! And yes, there are such packs out there!
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May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view--E. Abbey