i find it hard to believe that dispersion is the only variable accounting for differences in a speaker composed of cones as compared to a another speaker which has none of them. can you suggest a way of demonstrating this ?
It may be hard to believe but in the grand scheme of things when comparing 1000's of cones to all the panel/electrostats/ribbons out there then the radiation pattern is really what sticks out like a "sore thumb" as the one big difference overall.
Sure there are other differences and surely different transducer materials will make different spesakers sound different...but we are talking 1000's of speakers - so in general it is the raditaion pattern that is what remains markedly different.
I expect that Mirage or other omnidirectional or dipole speakers might be closest to the panel sound...although a large surface causes beaming in the forward direction (something cone speaker manufaturers try to avoid by using multiple sized cones for each frequency band) so perhaps horns (which can have a controlled directional sound) might be closer.
Perhaps Duke can suggest a speaker that you should try that will be closer to what you hear from panels - not that you may like it more ...but just to demonstrate that cones can be made to sound much more like large surface panels if configured in a certain way...