@wspohn - "I tried it later on my Electrostat system and it works there too - pretty sure it wouldn't if it was a hybrid speaker mating a cone woofer with the main panels."
My JansZen Valentina hybrid ESLs are the exception. I shopped for Martin Logans for years and never could get past the less than perfect integration. The M/Ls have gotten somewhat better lately.
The JansZen's integrate the two driver types flawlessly. Maybe it has something to do with the D'Appolito MTM design and/or its crossover approach, but the integration allows piano to play through the full range without any crossover or timbre change evident.