I think I'm qualified to speak on this from a body shape and pack load standpoint, I'm no pack maker, but I do own a bunch of high budget packs and I have hauled a lot of deer and elk out of the woods with them....and I have been a complete slob body as well as fit, currently sitting at 45 years old and 34" waist.....so middle of the pack now.
For me it ALL revolves around how the hip belt can be loaded and the weight removed from the shoulder straps.
If you start with the hip belt too low, it'll be way too low once loaded.
It takes a few tries to get the yoke to belt right when loaded and I THOUGHT I've had it right unloaded only to find that I had to lower the yoke once it was heavy (#80-120).
I LOVE the design of the Kifaru bags and the way they fit the frame, but for my shoulders, the MR yoke on the NICE frame simply works better. I use both, but if I know I'm coming out over #60 in my pack.....the NICE yoke just works better for me.
Everyone is different and I imagine Aron could point out what I'm doing wrong...but I know what I know from experience, not the net.
Load that bitch up heavier than you ever expect to carry and see where it rides. You'll want to know the measurements.
It SUCKS when you're solo 3 Mike's deep getting a 100 pound pack on and standing up more than a time or two.
Think you'll never do it? Get #80 loaded and look down at that little bag of meat and ask if you are willing to do an extra 6 miles for it.....it'll be on your back.