I don't do curves Mark, only in the past with ex-girl friends and now the wife, and it tends to mean a clip around the earss, and they get touchy if we spot differences
More seriously I think it's something at the top of the curve that gets missed with conventional densitometry. It might surprise you that we rely on a more visual tesing approach here inEurope with almost no densitometty. JohnBlakemore, perhaps the finest everv exponent of the Zone System does everything with visual comparisons.
My own view is those using densitometers have no confidence in their own abilities they never leave the nest and fly . . . . . . .