I've listened to the Zu Tone and the Zu Druid on the same equipment in the same room with the same music.
First, understand, neither speaker has a crossover. None. The full-range driver in each is naturally rolled off on both extremes. The supertweeter is rolled in on a simple filter at 12kHz. The full-range driver sees the signal directly from your amp, no electronic elements, passive or active, in the way. An external crossover of any kind is unlikely to be anything other than a step backward, especially if using SET amplification.
The Tone and the Druid are quite similar sounding, with the exception that the Tone does not go as deep, and that is apparent. The bass it has is fast and beautifully defined, however, as is true for the Druid. The Druid has the same footprint as a Tone on a stand, but its cabinet includes Zu's Griewe model and delivers the bass extension as well as some tunability for the bass character.
I've also heard both speakers used with Zu's excellent Method sub, which is the only subwoofer I am aware of that I could recommend for use with Tones or Druids, due to it having the speed and transient detail necessary to match the same characteristics of the Zu full range driver. It's a tough call whether 2 Tones + 1 Method is better than stereo Druids alone. The Druids would be cheaper, take up less aggregated space. The Tones + Method would go deeper. There are some differences in the FRD used in the two speakers, so overall, a pair of Druids have discernibly better balance, resolution and tone than Tones. Druids + Method are more impressive still, and that gets you 2/3 of the distance to Definitions at 1/2 the price. The Tone is not more accurate than the Druid, but it is a little different and I can understand some listeners being attracted to Tones + Method. If you do that, you NEED good stands.
Phil