I tried a out a kifaru lat year with the new duplex lite and although I do believe their lumbar and hip belt are best in class, I just couldn't get the shoulder straps to fit comfortable. I also felt like a heavy load was not tight against my back. I will say I love Kifaru and still want to try another pack as I really want to use a Kifaru pack, but there is no denying my SG fits like a glove., so I went back to SG. That being said I have had a minor issue with the Xcurve hip belt and had a little discomfort only on the right side right on the front of my hip bone. I finally contacted SG and Pete took care of me and sent me out a brand new hip belt to try out and see maybe I had a bad hip belt. Although I was skeptical I tried it out and it instantly felt better. I later compared the inside foam with my older hip belt and noticed that they changed the foam apparently recently. The old hip belt was a firm foam and was dual density. the new belt feels a little softer and is single density and so far has made my pack a dream again. Funny how we are all different. i feel the SG really shines with the heavy weight over 80lbs and I have tried KUIU, Kifaru, and Exo K2.
Also, I feel SG packs are second to none with keeping the pack against your back and not sliding down. When I put 80lbs - 100lbs and secure the straps I never have to worry about re-adjusting and moving the pack back up on my hips.