yes i will assert that any electrostatic, WITHIN ITS FREQUENCY RESPONSE BANDWIDTH, will create the sound of an instrument, in a manner more realistic than any cone design.
(in the above quote the capitals were added for emphasis)
Hang on ....you are now adding a huge caveat to your previous categorical statement that almost any electrostat/ribbon/planel speaker will sound better timbrally than any of 1000 audiophile quality cone based speaker designs.
I don't think that any test would prove anything except you prefer by far the sound field from a large transducer surface over "point source" designs. To me this is a perfectly reasonable position to adopt....they inevitably sound different and excite the reverberant field in a fundamentally different way.
since this experiement has not occurred you and i are engaging in probabilistic statements. such a test is not definitive, because it is possible that two listeners may differ in the outcome of such a comparison. do you have any ideas ?
By calling your own arguments "probabilistic" and by adding a big caveat, you are actually undermining your own previously categorical position....but I don't really care about that....you are welcome to worship electrostats/panels/ribbons and I wish you well in this area and many years of listening pleasure, I don't doubt they sound much better to your ears/preferences and it would be ridiculous for me to insist you are wrong to like what you like.
I am simply trying to get you to recognize that the major difference between ALL cones and ALL Electrostats/ribbons/panels is the different sound field they create and the different room reverberant field that they excite; therefore what you are describing as "less inaccurate timbre" from any of your prefered designs is incorrect. To me there are good bad and terrible timbre speakers in all of these camps and a particularly lousy electrostat will certainly not sound "less timbrally inaccurate" then some of the best cone speakers (even though the sound field and reverberant field is bound to be different).
IMHO, if we wanted to explore the most accurate timbre then the discussion would inevitably involve headphones rather than speakers => this allows you to get rid of the effect of the room and work with very light weight transducers working in an extremely linear operating range that far exceeds what can be done with any speaker today. Unfortunately this means the sound appears to be in between one's ears and is therefore very far from a realistic presentation even if it can be the most accurate.