Best Electrostatic loudspeaker?

Essentialaudio - thanks for the info. If not asking too much, can you arrange to have some U-1PXs delivered for my next birthday?

Sure, when should I look for your check?

Has anyone listened to the Electrostatic speakers from Sanders Sound Systems - Models 10c or 11 ? Appreciate any comments or feedback regarding these speakers.

Wilfredt- Sarcher has some Sanders or the earlier version, I forget the name. You might look at his system and ping him. I started with 'stats back in the early 70's and could never find midrange comparable on other speakers, but using the original Quad, I WAS limited by restricted dynamics, bass, beaminess, etc. I used ribbon tweets, and subwoofers, which I could never integrate properly. Still have them, awaiting restoration. Then went to a Quad 63, mod'd by Crosby. That speaker overcame some of the shortcomings of the original Quad ESL, but to my ears, it didn't have quite the same coherence in the midrange. Still have those too. Finally went to horns, circa 2006. Dynamics not an issue, but getting them right has taken time, and they are much more finicky about the associated equipment. At some point, I'll reassemble some Quad stuff, just for kicks (I wouldn't mind doing a slightly updated version of the HQD). I did like that original Martin Logan curvalinear panel and back in the day, listened to my share of others, including the KLH 9 and Dayton-Wright.
Soundlabs probably makes sense. Haven't heard the newest incarnations of the Quad either.

Wilfredt, I own the predecessor to the Sanders Sound 10b which is the Innersound Kaya. The Kaya's are a little bigger than the 10b and/or 10c. These speakers do not lack in dynamics and can handle high SPL with no fear of arcing like Quads. They are also full range with no need of a subwoofer because they basically have subs built in. They need a powerful amp to drive the electrostat panels but come with an amp to power the woofers. I'm using an Innersound amp for the panels and it drives them well.

I have heard the 10b and 10c at RMAF a few times and they sound very similar to my Kayas. Driven by a good source these are very good speakers.

They are very directional in the high frequencies because of the flat panel. This results in a one person sweet spot. If you usually listen in the sweet spot then this is not a problem. The benefit of the highs being directional is there is less interaction with the room.