It seems to me, and understand I don't have any experience with cuben backpacks or ZPacks, but from what I've seen Zpacks are made for UL wts. and minimal volume gear. Also seems most of the carrying wt is on the shoulders and not a whole lot of wt gets transferred to the hips. I know it is VERY Appealing to have a 6 oz or less pack, but DO UNDERSTAND that calls for a very specialized kit on a thru-hike with virtually NO FRILLS or many features in the backpack! They are not for everyone and are, IMO, probably not the best overall pack for thru-hiking when someone is newly downsizing to UL or has little experience with minimalist type gear. For short duration, like long weekends or someone who is experienced with UL wt and small volume(compressible) gear absolutely doable pack. Just my 2 cents.