Wide dispersion + high efficiency + detail + coherence in a speaker?

what is the problem? wide dispersion plus high efficiency 
or wide dispersion plus coherence?

Vandersteens have a tiny sweetspot
MBL are lifeless and are not coherent at all.
Ohms lack in dynamics and detail.

If coherence is truly your biggest point, then you may be better off looking into the idea of designing and building your own speakers. If you are willing to look at something open baffle, then your degree of difficulty will be reduced dramatically - no enclosed box to design, calculate for and try to build...OB can be done much more simply and inexpensively.

But, if you’re looking seriously at coherence then you’d also in fact have to rule out passive crossovers. They can really do a number on the entire crossover zone. They spoil stage coherence, dynamic coherence (by robbing lots of power from the amps) and also tonal coherence which can affect things like clarity, timbre and vocal sibilance and intelligibility.

You will need active crossovers, digital are best...standalone active crossovers that use passive parts are too limited to be of any real value. But Behringer DQX, or Crown XTi-2 amps or the DEQX with the amps of your choice And a good conditioning solution that works for you and you can have real coherence that few other systems are capable of even at many times the cost.

I’ve done all this myself. I went with the Crowns and a buttload of Alan Maher Designs to completely tame the (mostly) digital noise and - presto, it’s all to die for.

Oh, and for wide dispersion you might want to consider excellent quality dome tweeter designs (beryllium??) rather than ribbons. Ribbons may have better detail usually, but they may also tend to beam a bit more than cones or domes.

None of the 3 speakers mentioned/listed would be considered a "High efficiency " speaker (HE). Generally speaking HE would mean a sensitivity of at least 94-95 db with 1 watt at 1 meter and an easy to drive impedance load. Typically 6 ohm load or higher along with a relatively flat impedance curve that avoids dips into the lower impedance range and avoids steep phase angles. Vandersteen has a relatively easy speaker load but has only modest sensitivity (less than 90 db).  There some speakers with 4 ohm nominal  loads that have  generally flat impedance characteristics  and found to be easily driven (examples,  Tekton and Horning). 
Charles

I never understand why dispersion Is important to people. When I do any serious listening I sit down and listen. In fact I consider lessxdispersion a good thing as you get less room interaction. If you’re looking for a party speaker, then yes dispersion is crucial. But nobody is critically listening during a good party!

You should should check out Living Voice OBX RW speakers. They are effecient/sensitive with a benign impedience curve. 94db and the impedience does not drop below 6 ohms at any point. In a small room, 12x14 or so,  8 watts is fine. In a larger room 20 - 30 watts will do wonderfully.

They are the most coherent speaker I have owned and deliver uncanny musicality. Wonderful wide sweet spot and soundstage to boot. The midrange is very open and lively with wonderful tone.

The bass while not 20 hertz deep and thunderous is full bodied and present down to about 30 htz. They are rather small and easy to set up in most any space.