The midrange is the most important driver.

@czarivey, Fried used a (the?) famous maker's kevlar drivers for while.  Unfortunately, they just didn't sound or measure well.  As Bud spent 1/3 of the year in Europe, he popped over for a visit to the factory in France, and demanded a set of measurements take place in his presence.

You can read between the lines, but the next iteration of the Fried line employed Gefco drivers

My guess would be that the carbon overlaid balsa wood driver in the Vandersteen Model 7 Mk.2 would be very difficult to beat, especially for quickness of response, as midrange drivers go.

From 500 Hz to 2000hz is the actual heart  of the Miidrange .
Low midbass from 250hz, upper midrange - treble all  the way to 4000 kHz
. The Midband without Any doubt is the most Critical part of all music 
Getting this right should be paramount, that is why Harbeth dedicated so much time To his patented mid  driver. One Step better and I feel the best drivers in the world From $2500- $32,000 a pair are the Voxativ wide band drivers .
Sonic purity is paramount in any great Loudspeaker !!

I find the idea of two different drivers doing the relay-race baton handoff in the midrange, that handoff being arranged via a x/o filter, a very undesirable situation. Fortunately, one needn't accept that scenario. The Eminent Technology LFT-8b's "midrange" magnetic-planar driver has a symmetrical 1st-order (6dB/octave) filter at 180Hz, and another at 10k. 180Hz to 10kHz from a single driver, with no filtering! Actually, there are two of the drivers (to create a line-source, and increase maximum SPL capability), one stacked atop the other, with a ribbon tweeter beside them, and an 8" dynamic woofer in a sealed enclosure below. For $2499/pr!

@bdp24  Three comments about the LFT-8b

1.  From you comments, it seems that they have similar placement restrictions to other "panel" speakers in that they sound best 5' out from the wall which is a problem for a lot of people
2.  Eminent Technologies seems to be well under the radar.  Not many people have heard them and there aren't a lot of places to go hear them...so, for a home trial, its probably going to cost a couple hundred dollars to send them back if you don't love them.
3.  If you buy a maggie and then decide in two years to move on, you will probably recoup 75% of your purchase price because of their repuation and strong following.  I suspect that your financial risk is much greater with the E.T. LFT-8b

As to the "midrange" question...whichever  combination of drivers/crossovers/boxes allow the reproduction of the piano, the acoustic guitar and the voice to be done in a way that provide the "your are there live" experience is the right starting point....but I think there has to be a recognition that the way I interpret/process the sound of a piano may be different than others...hence, why different solutions work for different people.