Single driver speakers. Are they worth considering ?

I see Charney claims 20hz-20khz with no roll off on the top of the line speaker. Some of the others in the 30's to 20khz . I see no measurements on their site to substantiate this. I don't suppose there are any third party measurements anywhere? 

Erik,

I've heard a lot of wide-band/full range drivers used very successfully in multiway systems.  Some were, as you discuss, assisted by a woofer, others were assisted by a tweeter (most commonly with large diameter full range drivers) and some with both a woofer and tweeter.  Most of these were custom-built systems.  An example of use of extended range drivers in multi-way systems includes the SoundKaos Model 42.  By using simple, first order crossovers and allowing the crossover points to be away from the critical midrange, fullrange drivers minimize the negative aspects of multi-way designs. 

“I don't suppose there are any third party measurements anywhere?”

You’re unlikely to find third party measurements cause speakers like Charney are outside the scope of CFO (Chief Fun Officer) at ASR 😂

They would happily measure them  if anyone wanted to send them or if the company did. They are interesting looking. 

There is also a YouTube guy, Erin's Audio Corner,  I bet he would like to put one on his new Klippel. 

https://www.erinsaudiocorner.com/