I've been thinking about this talk of load lifters and trying to picture just how they work. When looking back on all the packs I've used over the years that employ load lifters, it occurs to me that never once did they function as actually "lifting" the load. Every time I can recall they simply pulled the pack closer to the shoulders. So I question the efficacy of load lifters actually "lifting" the load. If you think about it, it doesn't make sense that they would interact with a frame to transfer weight to the hip belt, since they are either pulling the top end of the frame or spar closer to the back, or else, if they are located a little further down behind the back, pulling the top half of the pack up, away from the hip belt. The only way that the load lifters would effectively affect the distribution of weight of the pack would be if they redistribute the weight onto the shoulder straps, which is not how they are usually described as acting. So I think the name "load lifters" is a misnomer, and that they should be called something like "weight huggers" or "load cinchers" since that is more of what they seem to do.
I think a real load lifter would be located at the top of a spar or frame and reach down along the length of the spar or frame, and when you cinch the strap on top the fabric would pull directly up the spar, not horizontally to a shoulder strap. For this to work, however, the back of the pack would have to have some give, otherwise the lack of movement would render the pull of the strap ineffective.