Since you are obviously considering spending the big bucks, here are two more speakers to consider.
Revel Salon, would be my second choice, at around $12K new and $10K used. Great build quality, very accurate, very great bass response, and very good imaging and soundstaging. However, if you don't like the WP 7, you probably won't like the Salons, as I think they are somewhat similar, so....
My first choice, although it is more expensive, is the Avalon Eidolon, at around $22K new/$12K used. The bass is ever so slightly rolled off, but the imaging and soundstaging are incredible. Assuming you have first class electronics, it is tough to beat the Eidolon, IMHO.
The Eidolon diamonds are about $10K more than the regular Eidolons, and supposedly sound even better, but since the regular Eidolon sound so good, save the money for better electronics!)
FYI, I have no axe to grind here, as I own the Revel Studio, similar to the Salon, but slightly smaller. (The Studio is very good speaker at a bargin price. Again, my opinion.) However, a friend has the Eidolons, and they are a step above my Studios, (although they should be for twice the price). If I could have afforded both the speakers and the subsequent electronics upgrade, I would have bought the Eidolons.
(I keep mentioning the electronics, because the Eidolon speakers are very revealing, and nothing but the best works well with this speakers. Plus they like lots of power, although, so do the Salons and Studios.)
My two cents worth anyway.
