I used a men's Quest on the JMT, southbound a couple of years ago. It weighs just under three pounds and handles loads up to 35 lb as comfortably as any pack I have had. After my resupply at Muir Trail Ranch, I was near 35 lb. and it handled the weight a lot better than did I. I don't have any experience with, or comments on, on the woman's Quest though. I think it is a pack you might want to at least consider.
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May I walk in beauty.