I've noticed a recent trend in packs, the "Saggy Bottom Pack" phenomena. Next time you are at the local crag, check out all the packs that sag way past the wearer's butt. At first it's hard to see, but once you notice it, you can't help but see it. Of course it's much easier to make a pack that way; a pack that as your shoulders move right the pack "tail" wags left; a pack that has a pivot point at the hip belt that does not suck the load into your back for climbing efficiency.
One of the most frustrating, and eventually most rewarding, things we did was design for two detailed oriented ladies that hated the "saggy bottom" packs. After much design work, we have one of the few pack lines that support the load with a sound structure. Our Omega Pack's hip belt directly supports the vertical load through the pack frame, and our Tau and Delta series packs' hip belts directly connect into the sides of the packs, pulling all of the contents into your back. This is much different than other manufacturer's hip belts that run between the back panel and a small piece of fabric. It is improbable that the hip belt can effectively support a load transferred from the pack's main compartment to the flexible back panel/attached layer of fabric and then to the hip belt (unless the pack is stuffed with gear until it's bursting at the seams, and even then it's unlikely to effectively support the load).
Years of hard work pay off to provide an efficient, load carrying Figure Four pack that connects the load to all of your movements, both climbing and hiking.