Quad ESLs - I have some questions


Recently I heard the latest model Quad ESL, 2905 I think, and it was a love at first listen kinda thing.  Of course I began looking at used Quad ESLs, and I am curious what the significant differences are between the 63s and the later models like 2805s and 2905s?  Used 63s are in my price range now, 2805s etc would require some patience, so I'm curious if the SQ, reliability, power handling, or other differences are worth the additional cost?  W/r/t 63s, should I be wary if they've been rebuilt. or should that be comforting if the rebuilder has a good reputation?  Anything else I should know?

The 2905s I heard were powered by a Bob Carver Crimson 275, the dealer said my BAT VK-55 would also be a great match.  I listen to singer/songwriter/acoustic/Americana/indy/alternative music with some experimental, jazz, chamber, and classical piano thrown in.  Think First Aid Kit, Jeff Parker, Wilco, Michael Kiwanuka, Gordon Lightfoot, Everything but the Girl, Anna Meredith, generally 85-93 dBs.  Room is 12x20x8, set up for one listener, fairly well treated.  Current speakers are Thiel CS-2.3s.  Also considering Zus and Devores.
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I’m listening now to my Bache Tribeca’s and wondering if I would even bother to connect the Quads back up again. What’s special about it is the whizzer-less bamboo wide band driver. With nothing in between the driver and my amp it’s very smooth and coherent. 
If we're talking about 'stats you can't forget Sanders Sound Systems model 10e. A bit pricier than the Quads, but offer the best of both worlds. The most coherent sound from 170Hz to 20kHz+ and a very well integrated TL (transmission line) woofer system. Also, SSS includes an LMS (loudspeaker management system) that allows lots of adjustments (EQ, crossover, room correction and driver time alignment). And... they play plenty loud and are virtually indestructible with lifetime warranty. Sanders has the best customer support I've ever experienced.