Electrostatic pros and cons.

The main pro I would say is the very low distortion with their air-damped diaphragm.

The strengths of electrostats usually include superb inner detail and articulation, low coloration, very good to superb imaging, and excellent pitch definition in the bass region. They tend to sound startlingly natural.

The smoothest measured in-room frequency response I have ever seen was a SoundLab panel set up in Roger West’s open-floor factory. They ran pink noise through it and I was watching the real-time analyzer display. There was no smoothing and no time gating. The curve was a gently downward-sloping virtually straight line, down maybe 5 dB at 20 kHz relative to 100 Hz, spoiled only by a 2.5 dB up, 2.5 dB down jog at about 500 Hz.

The 500 Hz jog was narrow enough that it might have disappeared almost entirely with 1/3 octave smoothing, which is more representative of what we perceive than is an unsmoothed curve.

I asked Roger why he didn’t use these measurements in his marketing, His reply was, because someone else might get a different curve with their measuring system and accuse him of exaggerating.

When I was a SoundLab dealer, from time to time I'd have other well-respected speakers in the same room.  Usually these other speakers were more efficient than the SoundLabs.  But invariably I'd find myself turning up the other speakers even louder in an effort to hear the details which were clear on the SoundLabs even at their lower sound pressure level. 

Duke

Erik, I’m aware that there have been measurements of electrostats that apparently showed chaotic diaphragm behavior. Such chaotic behavior would be inherently non-coherent and therefore fall off more rapidly with distance than the signal being produced coherently over the entire diaphragm, which approximates a planar source up close, transitioning to approximating a line source or sometimes a point source as the distance increases.

In other words, if this chaotic diaphragm behavior is "noise", I think the "signal to noise ratio" of an electrostatic panel improves with listening distance, because the noise does not propagate as efficiently as the signal does.

For example, if the bias voltage is up a bit high on the SoundLabs (and/or if your humidity drops significantly), you can hear a waterfall-like sound up close to the diaphragm.  This is an incoherent noise, and it does not propagate to the listening position.  You can play music at very low volume, down around that waterfall noise floor when you listen with your ear up near the panel, but move back to the listening position all you hear is the music at very low level; the "waterfall" doesn't make it that far. 

Duke