mm.. actually, i think the Mg alloy does make a difference.. i don't really abuse my equipment, but i don't pamper it either.. there was once i was shooting at a water fall when i slipped. my reflex was to push my hand back to balance and in doing so i slammed the d200 into granite.. the granite actually chipped off, but the camera was fine. pretty sure a plastic body wouldnt have fared so well. i routinely bump my d700 around, and it shows on the baseplate and corners. i ve had both bodies splashed with seawater and sand, used in thunder storms, and had the d200 sitting in about 1-2cm of water for a shot... its reassuring to know(and convenient too) that i can just rinse it off under the tap. what matters to me is that i can concentrate on shooting and not have to worry about accidental knocks and misalignment from falls. i guess its the assurance that the camera won't suddenly die on you unless you really really screw up