Thanks Roosie,
I ended up going to a 25” stay which is clearly a much better fit for me. With the belt sitting up higher, the hip fatigue goes away (my PT wife corrected me, it was glut med).
I almost always hike with KUIU attack pants with a KUIU climbing belt. If I tuck my shirt in, it definitely helps a lot, but if I forget to tuck it in I encounter pinching and/or skin wear in front of my hips with heavy loads and/or long hikes. That’s common no matter what pack I wear, so I know it’s a belt issue. I’ve tried a few belts with no success in resolving it, and my skinny rear end doesn’t do a good job of holding pants up without it… so it’s a bit of a dilemma.
Okay, all of that aside, I’ve been using proper mountain packs for quite a long time, and specifically Exo now for a lot of years. This K4 truly is a massive step up in my eyes, both in performance (I can’t find a way to make it sag on me), design, and quality. Just looking over this pack, you have to take notice of all the small details that clearly indicate the amount of thought that has gone into making it something special. I’ll be the first to say there’s nothing on the spec sheet that jumped out at me as a reason to upgrade from K3, but after comparing the two the K4 is superior in many ways for me.