don't know if anyone has mentioned this yet but even "single driver" speakers have crossovers. Different parts of the cone respond at different frequency, so there is a mechanical, rather than electronic, crossover. "Whizzer" cones, found on some well known "full range" drivers are an extreme example. Only a headset driver is small enough to cover the entire spectrum without breakup.
Designs that chase one extreme (no crossover) at the expense of others (mechanical driver limitations) are not guarenteed to come out far far ahead, even if some exceptions can sound extremely good (no doubt ZU is one of these designs, judging from the accolades).
Chasing one extreme, however, may have the significant advantage of being highly differentiated in a forest of look-alike two and three way boxes...you and your guests can readily appreciate why they are different and be proud of it!