Does a Quad 57 sound like an Apogee Diva, Sound Labs M-1, or a Martin Logan CLS??? Not the ones I've heard! They all have things they're good at, but none of them are good at all things.
I was in love with panel speakers for decades and still hold some of them in high regard. Yet I have moved on because I have found some ribbon-hybrid speakers and certain cone speakers that provide qualities I was unable to coax from panel types.
Well stated, I agree having owned several panel speakers including the wonderful Sound Lab Ultimate One.
I understand Mrtennis love affair with the design. All the years I owned Sound Lab I was completely satisfied with what I heard. However, once I changed to my current speaker (dynamic woofers plus ribbons), I have no desire to go back.
My choice for panel speakers was back in 1989, when cone speakers and dynamic drivers in general were not nearly so evolved as they are today.
No doubt both technologies have progressed but modern dynamic drivers have reinvented themselves completely. Distortion is a fraction of what they once were, especially high frequency diamond tweeters, ribbons and ceramic midrange.
In my opinion, many of these modern drivers sound more free, uncolored and faster than previous electrostatic designs. I'm sure advances in chokes, wire, capacitors and cabinet design play an equal role, but whatever the forces at play we have some stunning choices today.