While live Classical music at times may reach 100dB, it is for only brief lengths of time. Hard Rock bands on the other hand may average 100dB for an hour or longer set.
A speaker which does very well with Hard Rock music may not reproduce a String Quartet (or a harpsichord, one of my favorite sounding instruments) as well as does the QUAD ESL, and visa versa. Not exactly horses-for-courses, but not far off.
I don’t find the idea of different loudspeakers excelling at reproducing different kinds of music at all a radical notion, any more than the idea of different automobiles excelling at different kinds of driving and roads.
I remember in the early-70’s the JBL L100 being sold as a "Rock ’n’ Roll" speaker. I hated the L100; it was extremely colored (in what J. Gordon Holt termed "Vowel colorations"). Vowel coloration is one thing you don’t want in ANY loudspeaker. At that time ESL’s were the only speakers I had heard which didn’t sound colored to me. ESL’s reproduced human voices and acoustic stringed instruments like no others. For those who listened primarily to vocal or acoustic string instrument music, an ESL was an excellent choice. If it was pipe organ music, not so much.