I still have my Coherent 10's from my earlier post 5 years ago, time flies! I also have a pair of Volti Razz. Both are excellent, fairly similar with some slight differences.
Voltis dig deeper and tighter in the bass than the Coherents, and they can scale up the sound much easier when you crank it. Volti are also more room friendly, those Coherent 15's on USAM are going to need some space. I tried the Coherent 12's and they were a bit big for my room, I stuck with my 10s.
That said, my Coherents have the most clear and engaging midrange of any speaker I've owned. Being point source, they do sound more coherent (derp) and organic than the Voltis.
Both speakers are tunable. Volti gives you an extra set of resistors which I have not had the need to use. The Coherent crossover is infinitely tunable. When I received the 12's they were way too bright, and Frank showed me how to swap out the crossover resistor with a simple screwdriver to get the tweeter balance the way I want it, worked like a charm. The only catch is you have buy your own resistors.