exactly, drurb.
i agree completely. what you
want is a matter of your taste. a loud orchestra bassist might want something other than what a mainly pizz player would want.
yes,
stiff resists and conducts.
dense and
heavy ultimately takes more energy to move because it is inert, but once moving will sustain longer for the same reason.
light is responsive, it is easy to move but will decay more quickly. e.g., a light soft wood isn't stiff enough, a hard denser wood like a drumstick is.
so the theory would be:
light plus stiff-resistant-conducive is good for making sound on the bass in an energy-efficient way: easy to get moving with but firm enough to make the bass vibrate and ring out. that is great for pizz especially, and tends towards a brighter sound. but if you play arco on a large, heavy, and dark sounding bass you might actually prefer the steel endpin because that bass might need its additional stiffness and inertia.
interesting, last night i A/B'd a light carbon fiber end pin (it has a light synthetic rubber socket) with my older steel endpin (with heavier hardwood socket). the difference in sound was really amazing. my bass vibrated noticably better and fuller with the lighter pin.
right, they're just sort of "guidelines" anyway...