I checked out the Zaph Audio site... that's from 2008.I have, it is not a well-engineered driver. And it isn't even cheap. I have intended to remeasure, but the on-axis performance is very poor, and the off axis has odd behavior as well.
Zaph Audio has measurements:
I was never able to get the tweeter and woofer integrated. I have debated going back and trying DSP crossovers. It isn't an elegant design, and none of the issues inherent to coax seem to have been addressed like proper loading of the tweeter into the woofer cone.
Full range and coaxial are apples to oranges. And a whole new set of tradeoffs.
Seas does make a very competent looking coaxial driver, but it is a midrange only, not a woofer, which solves one of the problems of coaxial speakers (the misnamed Doppler distortion) with the tradeoff being no bass extension.
Not what I said at all!!! Some of the coaxials are a tweeter stuck in the middle of a woofer, coax doesn't magically fix anything, in fact the opposite at times. Genelec has done great with Coax too. Many others too.
Coax doesn't make it easier to build a speaker that sounds good. It is one way to go though.
Do you think Seas may have fixed the issues in the past 15yrs?
Ok, so I guess the hate for coax is more out of frustration.