Not sure how much control of the “cant/fit” of the belt can be achieved by different types of connections between the belt and the belt buckle. The good ones I’ve seen do simplify tightening the belt, and help maintain its conical shape. The goal IMO is to keep the back of the belt from sliding downward, and the buckle and belt front from pulling against the tummy. If that occurs under one’s usual load, the suspension is not working, regardless of the design, make or model of pack.
For those with steel-like musculature, that may make little difference, and not substantially hamper comfort. But for many, it creates discomfort in the short run, and injury to the spine in the long run.
The conical shape of most belts no doubt helps to keep a pack from slipping downward. However, with enough weight and enough distance, the pack will slip. And since different body shapes will fit different cone shapes, there is no ‘one size fits all.’ If the front of the belt is free to ride up, the back of the belt is free to ride down to some extent, no matter how well the belt fits the body contours, and how well the straps connecting the belt to the buckle help maintain the belt’s conical shape.
At one time, Osprey had ovens in pack shops that heated up the foam in belts to mold to different body shapes. But the full suspended mesh back bands were strung so tight, they were inferior to a simple foam back cushion. More recently, Osprey has tried to limit the amount that the front of the belt can ride up by stiffening the belt, and making the connection of the back of the belt to the pack more rigid to keep the front of the belt from riding up. That seems to be a work in progress, as haven’t seen too many raves about Ospreys lately.
Despite all the focus of BPL on lighter and more compact gear, a lot of the packs in use are quite large, and do not seem to have shrunk very much. This led me to begin by limiting the size of the pack, and then finding and using gear that will fit into it comfortably. With lighter gear becoming available, along with MYOG, this can be accomplished. The tough part is to either find, or design and build, a pack suspension that addresses the above issues, especially taking the pack weight off the back and placing it on the “hips.” A look at skeletal shapes suggests that this means resting the weight over the Iliac crests.
It is said that this places all the weight on the feet, legs, knee and hip joints; however, that’s all we have between the body and the ground, so that is where the weight is going to fall regardless. The goal is to get the weight off the back. Knees can be replaced (granted not as a first resort), but spines cannot. Concern for both suggests that the real road to pack heaven is to lighten up. Along with a very light kit, this also means food caches no more than seven days apart, or less; footwear and pack suspensions that remain comfortable for extended periods; and avoiding camping near bear populated areas that require heavy and bulky food canisters. This involves trying before buying and test runs, and often it is not possible to ‘try before you buy.’ For me that has been the most expensive part of backpacking, but well worth it for the enjoyment. And unlike footwear, packs and suspensions are susceptible to MYOG, and that cuts way down on the expense of repeated pack purchases.