Make no mistake, there is nothing gentle about the killing of JonBenet, but her death is a far cry from what a sadist would have inflicted.

Not even a sadist just "starting out"? I would think there might be a broad range of sadistic behavior. The extreme end might be the severe behaviors you've suggested. Since there was no need for all the 'extras' in the killing of JonBenét (stun gun, hand-tying, head blow AND strangulation as opposed to just one or the other), I cannot help but think we might be looking at the early stages of a sadist at work.