Floorstander suggestions to replace Usher S-520s..

My current setup is [a million different digital devices]--->switchbox---->headroom microDAC--->Rotel RA1062--->Usher S-520s.

This setup was designed for my somewhat large bedroom, where I did most of my listening. However, I have since moved to Santa Clara. I felt like the Usher's weren't filling the room entirely. So I went down to Century Stereo and listened to some B&W floorstanders, and they even had my exact RA1062 for me to audition them with. I was completely blow away. The upgrade here sounds huge. I was listening to the B&W 683 and 684.

So I started looking around audiogon for some deals on used stuff and I found some b&w P-5s and some 602s3s, both which I am quite interested in. As you can tell, my budget is probably no more than 700, i would prefer used and I want a floorstander and know very little about floorstanding speakers as pretty much all of my research has been done on monitors. Anyone have any suggestions for other speakers I should be considering?
Rega R3's are hard to beat for the money. Love mine. They're in your price range.
Worth having a look at the KEF IQ series which I much prefer to B&W at this price point.
AV123 X Static(?) speakers. Heard them at the RMAF.
They are floorstanders that are open panel on the top with sealed bass units. I think they were around $800pr. Sounded better than many speakers in the $5000 to $10,000 range. They seemed to be a tremendous bargain. Very nicely voiced.
Have you considered adding a powered sub to your existing system rather than getting new speakers? A good sub can be musical if set up properly and provide more low end than a pair of floorstanders in your price range. I preferred the mids and highs of the Usher S-520 to the B&W 685 when I auditioned them, but everyone's ears are different.