But you see, Brett, the reason it was exciting to swap the Dawn for the Z Pack was because I was able to shave 9 ounces without affecting either safety or comfort! Both packs carried very well. The Z pack isn't bombproof, but then, neither is the Dawn -- so no sacrifice at all in my book. It's rare when one can shave off more than half a pound without giving up anything. :)
Separately, reading Michael's post above, frameless packs -- or packs with easily removable frames -- from Fanatic Fringe, Gossamer Gear, Mountain Laurel Designs, Six Moon Designs, ULA, Z Packs, etc. are all very worthy UL candidates!