I am going to add the KEF Ci200RR-THX to my recommended list. It is the only proper way to build a ceiling speaker in my opinion especially for height channels.
Someone correct me if I'm actually wrong, but I'd go a few steps further:
-Non-coaxial designs for height speakers should be categorically rejected unless you have a single listener/position.
-The coaxial (dual coincident/concentric) design also solves the issues of center channel speakers and should be used unless you can place a vertical MTM behind your projector screen.
-Ceiling and Floor bounce are often the most ragged for most speakers which coaxial speakers also fix, so all things being equal coaxial speakers should be chosen for their inherently better design.
-Coaxial speakers aren't inherently acoustically compromised like the dispersion on 2 and 3 way speakers that has lobes where they should busted. Thus again, all things being equal the coaxial should be chosen.
-If you are mounting speakers on your walls for immersive audio, coaxial speakers can take up less room, and they can be mounted higher if needed and tilted down without having as many issues with inconsistent ceiling reflections... again, should be chosen all other things being equal.
-IMD and distortion caused by an air gap isn't a problem with modern coaxial drivers and those issues were solved 10+ years ago by Genelec.
Valid reasons to not use a coaxial:
-Currently main monitors can outperform coaxial speakers if a user decides they need extremely high SPL levels they don't for 'dynamics' because speakers don't act like dynamic range compressors and operating within their limits don't actually sound more dynamic. This is one use case where it could be correct to use a non-coaxial due to SPL requirements and operating things at extremely high levels.
-There is no coaxial that has dispersion as wide as some Revel speakers and this can be desirable when trying to make the soundstage larger.
I'm curious about companies that refuse to use coaxial drivers and would like to hear their actually legitimate rationale. Why are they making broken center channels? Why are they making broken sounding height speakers? Why are they okay with lobes?
Should we also accept state of the art prices for class A amps? Surround rot on archaic drivers? Technically they 'work' but they could be so much better.
At some point for an incredibly high price we should be expecting state of the art speakers that incorporate all of the things where "all things being equal" it's advantageous. (Non-parallel walls, flared ports, coaxial drivers, DSP correction, 3-way, minimal diffraction, maximum internal volume for the size, maximum stiffness without lowering internal volume, etc.)
Seems like a lot of companies simply rest on their laurels.