I think having the knot up higher from the bottom bait causes a weak point in your line. When you hook up on the bottom presentation. Maybe if you used a dropper loop for the drop-shot hook. You would probably lose some of the action on the drop shot bait though.

Do any of you fish the drop-shot up off the bottom. You know, like half way between the bottom and surface? I always bounce the weight on the bottom. I've let the bait fall with a closed bail and taught line with some success.