No disrespect to the Zu naysayers, but before we diss their full range drivers, we should read a bit more what goes into them.
Chief designer Sean Casey has taken the "simple and unsophisticated" concept and maxxed it with a lot if care and attention incl dopings and treatments. This has enabled him to produce a full range paper cone that is indeed "somewhat" not simple and not unsophisticated. He's worked hard at ameliorating shortcomings like shoutiness at higher frequencies, more even low frequency response, indeed more speed and linearity over the 2.5 octaves that the full range drivers cover.
Otoh, Sean is firmly in the camp of "go simple enough, but not too simple". So, while his drivers are taken beyong simple, he's still a fan of the concept that eliminating crossovers, keeping efficiency high, having as sweet and smooth an impedance curve as possible, allows a particular take on getting to the heart of the musical message.
So please, can we get past the urban myth that Zu is just a rock speaker, or a party speaker, or that full range drivers are by definition unsophisticated and an easy option. I think the fact that one of the top half dozen spkrs in the world, the 118dB eff Pnoes horns, uses the exemplary full range drivers BD, defies the criticism of this topology as some sort of inferior option.