Right. Anyone doing a physics major here?
I think the thing many people forget is that a string isnt just vibrating in one way, its more than one (hence why you get more than one harmonic when you pluck a string). Now, if your pickup is under a harmonic node, where there is NO vibration at that exact point, then your pickup IS NOT going to pick up that harmonic. Hence, you get less harmonics in your sound under a harmonic node. The neck pickup in a 24 fret guitar is probably under a harmonic node, but maybe not one thats audible under normal conditions anyway, so the difference might not be as noticable.
As for the difference being more closer to the bridge ya get, i can see that.
And just for reference, the human ear isnt a useful tool for assessing tonal constituents of a guitar signal. Get a decent oscilloscope.
But to be honest, the actual difference is negligable in any ways. It, as with most things in building and choosing guitars is a matter of taste.
S
PS: OOOOOOOOOH --> http://www.till.com/articles/PickupResponseDemo/index.html