Greetings Brian,
Thanks for taking the time to give us your list of priorities.
Based on your priorities, from the speakers you mention in your original post I'd suggest the Quads, paired with a very good amp. Electrostats give you unequalled clarity, especially at low to medium volumes. While it's true an electrostat won't play as loud, dollar-for-dollar, as a dynamic, their superb clarity means you don't have to turn it up as loud to hear all the details. Soundstaging is somewhat dependent on room set-up, but the Quads are capable of incredible soundstaging. You get the dynamic contrast by pairing them with the right amps - otherwise, electrostats can be lacking in dynamic contrast.
Another line that I think would work for you is Piega, suggested above by JTinn. He's more familiar with them than I am.
I was very impressed with Buggtussel speakers at the 2001 CES - they match up with your criteria quite well. Very high quality dynamic drivers in transmission line cabinets, articulate and lively.
You might want to consider the InnerSound Eros, which has superb imaging for one, is exceptionally dynamic for an electrostat (it's a hybrid), and has great clarity. Setup is a bit more critical than for the others mentioned here, but you can handle it.
I'm a dealer for another electrostatic line, the Sound Labs. Alas, most of their models are out of your price range. But Sound Labs truly excel at timbre and clarity, and you might find a used pair in good condition in your price range. Frankly, if you come across a pair of metal-frame Ultimate 2's (now discontinued), they'll soundstage better than the wooden frame models.
If I can answer any questions, let me know. Best wishes to you on your quest!
Duke
