So I'm guessing we'll have to put Wolf's test guitar on a ship in the ocean and sail it towards and away from the equator, while Pete jumps around precisely windmilling the same power chords with each change in mounting configuration.  Can we wait until hurricane season is over?

Just do it on a submarine!!

I also think it explains why Bob Marley's old les paul jr sounded the way it did!

I believe the pickups in Bob Marley's Gibson were subject to a rastaman vibration.
 
Bill, tgo

Groan...... :-)

I recall someone here had a decent analyzer...
 
old good thread

I own a  GOLDLINE DSP30 RM RTA . I also have an old White Instruments Model 140. My Rane RA27 works but is not expected to be as sensitive as the Goldline DSP30 RM and the White Instruments  Model 140  is , The Old Fellow , but   Built to Last  

The one @ Alembic most likely surpasses mine BUT This one is way cool  too !
 
http://www.rohde-schwarz.us/en/product/fsvr-productstartpage_63493-11047.html
 
Yummy !

OH. look! __here's  one on sale on eBay  
 
[eBay link]
 
 
Such a deal.
 
(Message edited by adriaan on May 19, 2015)

I would expect that a moving pickup would be akin to using different woods on the instrument. If you were to attach a string at either end to an infinitely dense and immobile object, you'd get the perfect vibration of the string. To me, this was close to what I got when I played a neck-through Modulus many years ago. The impact of different woods on tone occurs when those woods vibrate in characteristic ways to absorb some frequencies of the string's vibration.  
 
Since the pickup is detecting the relative movement of the string, any movement of the pickup will impact the output. If the pickup could be made to move with a particular frequency, then it could act as a filter centered on that frequency. If the phases were in sync, the pickup should attenuate that frequency. On the other hand, reverse the phase and that frequency should increase in magnitude. The reality is that you are unlikely to get a consistent vibration of your pickup and any movement will have an impact on all frequencies. The more significant the movement, the more significant the impact on tone.
 
With tone woods, their impact on the output will often be a positive one. I suppose a little positive impact is possible from serendipitous pickup movement. Personally, i'd rather have it locked down to the instrument. After all, whenever I am looking at a bass to consider buying it, the very first thing I do is play it unplugged to see what sort of natural vibrating tone it has. If I like that, then wouldn't that be what I want to amplify?
 
-bob

Everything you say makes clear sense bob ...and surely it's not a simple subject.
 
  Since you asked the question about what is heard  
unplugged...My thinking is that the vibrations heard through the air (and maybe bone conduction),
 are the inverse of what the pickup reproduces as the first wavelengths travel up the string.  
 The vibrations get complex soon , but it could be
a mid heavy acoustic tone would translate to a mid scooped amplified tone .
 
I like those modulus necks too.Especially with really good strings,
the fingers really come into play more as the gatekeepers of Tone.