Stuart Allie, your requirements are almost the exact description of the Lowe Alpine Zepton 50.
Dyneema, no mesh pockets - actually my main complaint about this pack was the tightish side fabric pockets, but reading your requirements makes me realize that maybe Lowe wasn't as stupid as I thought with their smooth stretch fabric pockets.
Major downside: only two sizes, the standard men's and the hd women's.
This is a true 50 liter pack, not 50 liters like others claim by adding up all their pockets etc. Good weight control, pack actually supports the weight, you don't need to use the weight to support the pack like some of the UL framed packs I've looked at, can handle I think up to 35 pounds. 30 pounds felt to me quite decent, not that bad, so could see going with 5 more at the start of a trip if required re food or water needs. I did a first test with this pack last week in Big Sur on an 8 day trip, which has some major scrub and brush, tight trails, etc (well, it does if you hike out of where everyone else always ends up...).
The best part: true frame, no playing with padding etc, weighs 2.5 pounds, handles weight quite well, stands a bit off back, feels like nothing in 90 degrees facing sun on 3000 foot climb. Lowe is good at what they do, the major drawback to this one is your torso has to more or less fit, either be longish, like mine, or super short. I got it, to make matters even more superb, at Any Mountain on sale at $120, minus a 20% discount on one item for signing up as a member. Of all the new gear I bought for this trip, this was by FAR the most superior and un-disappointing product I got. But Lowe has always been pretty good at this game. Very good shoulder straps, very good hip belts, I read people complaining about the mesh liners but I believe that was a case of user error or improper setup, I found nothing of that sort of problem.
This pack might not get you the cool UL cred but I can tell you I saw exactly zero UL types where I went over 8 days....
I did not worry about taking this pack off trail, hitting tight overgrown chapparel bushes, etc. I actually added some z-packs stretch cord to the back so I could dry stuff when I walked, though I wouldn't put anything there when going through the more tough chapparel areas, that won't work. (major props to z-packs for their bear/raccoon bagging cord, bear bag rock pouch, and mini locks and cords/connectors, good stuff there... that cord came in handy fixing some funky broken stuff I ended up with too)
The one thing I had to tweak was the bend of the top part of the wire frame, which had a bend that was too sharp for my back, so it poked me, but I just pulled out the frame wire a bit and stepped on it until it unbent a bit, that is some tough wire/frameing material by the way, took a bit of force to get that kink a bit less extreme, after that, zero issues.
Oh, I should add, I am absolutely NOT an UL or SUL backpacker, though I'll use any of their gear or methods that make sense to me. I'm firmly in the 'Light' backpacker camp.