IMHO...
First of all, Coldplay recordings are not as great as they should be.
Second, I think your initial post provides more insight than you thought - When the music is right they sound excellent. What other rock do you listen to on your Quads that sounds excellent? I've listened to DSOTM on a system that conststed of Quads and probably $100k of associated gear and IMHO it just wasn't right. Vocals, acoustic guitar - very, very enjoyable. Anything rock - not so much. Given the listening habits of this system's owner I'm sure this was more than fine with him. These are some of the tradeoffs when assembling a system.