>> I must say that I loved the perceived euphony of the Druid. Are you saying that I might feel it has gone or just lessened slightly?<<
I'll try to separate characteristics here. Druid has known midrange response anomalies that give it a bit warmer-than-real sound, which combined with the soft top end render it sounding what some people refer to as "dark." The v4-08 upgrade substantially removed this but traces still linger. If that kind of euphony is what you like, Superfly will lose it conclusively in favor of better frequency accuracy and clarity without ever sounding cold. You can always restore some of that darkness by mating the speakers to the right 300B amplifier;>).
HOWEVER, if the euphonic character you love is more like your reference to "...Ben Webster blowing a real horn stood in front of you...," well, you're going to get that, just more! That tonal density and ability to represent the full bite and burr of a horn with the musicality of having small dynamic changes utterly transparently revealed, and the holistic sense of a horn fully represented rather than torn apart by a crossover and represented by different drivers your head has to put back together -- that's "better" than Druid, conclusively.
More frequency accuracy combined with absolutely no loss in tone. In fact, you'll gain tone along with an even quicker jump factor and bass extension that retains transient definition as low as it goes.
I can't say yet about base Soul, but you have to look at Superfly as expanding the polar graph of favorable attributes of Druid while taking some kinks out of the circle where Druid had consciously-chosen, restricting compromise.
Does that help?
Phil