I tend to think you have to think about the speaker as a whole not just the tweeter.
Of the many speakers I have, I consider Dunlavy's the most transparent all around. I would say that there are speakers like certain martin logans which are more transparent in the top end, but not in the mids where, a lot of the music is. Depending on the crossover, a good deal of cymbal sound is in your midrange not just in the high end.
My mastering engineer that i trust the most once called duntechs and dunlavy's "as flat as you can get while still being listenable". Which means, with microphones speakers and everything else, if you had a completely flat freq response, you might not find it that pleasing.
There is a lot of stuff to read up on about why specs are usually nonsense and how measuring things is a really good thing but not everything.
Some speakers really pick stuff apart. that can be really addicting, because when you go to another kind of speaker you miss the detail. However, if you like a lot of kinds of music, a very detailed speaker for some people, makes, say, led zep, unlistenable.
I go all directions. I have dunlavys for referencing stuff i really need to pick apart, B&W's for stuff in the middle and quads for that lush midrange thing like string quartets. All my speakers sound good to me, but they have different strengths.
While the natural sound of musical instruments may not be harsh (though standing next to some violinists or trumpet players might convince you otherwise) the sound of recordings is very different from life. Many recordings are hyped and all are voiced around the speakers they were being monitored and mixed on. There's no standard. That's just life.
I wish it were easiler to say "yes you must have this and sacrifice this" but there are so many aspects to the synchonicity of the audio chain it becomes, like everything discussed here, a matter of personal preference.
