B&W 685's Vs KEF LS50

I apreciate all the feedback, just to clarify, I had the B&W 685s before the Nova 300 and realize they are small for the WPC of the Nova 300 but the clarity and sound stage is remarkable, especially with a decent sub in my medium sized room. I'm trying to stay under 2k if I upgrade but could be talked up to 3k. 
B&W 700 S2 or something like it is on my radar but I have heard remarkable things about the KEF LS50s and was curious.
As Chris R said it's probably a case of too close to be considered a real upgrade

Bingo, that's what I suspected but needed some empirical data. I hadn't thought about the return policy idea, I'll look around and see who has that. Cambridge, amazon?
I think paired with a sub this might be a perfect fit but it would be nice to get a test drive

Important correction-I have the 686's not 685's
Thanks everyone for their input, here's my final consensus: I did break down and purchase a pair of LS50's directly from KEF USA. Although the KEF LS50's have remarkable clean sound and a good soundstage I was kind of underwhelmed when compared the the B&W's.
I gave them a good long break-in and listen, tried different placement, etc. but in the end the B&W 685's had a much richer and full sound, not just to ears but a couple of guest listeners as well. The sound stage was broader and more inclusive of mid-range and vocal/guitar notes. 
I'm not saying they aren't good just not a big improvement, more of a lateral move if you know what I mean.
I also found that at least for my ears, the KEF's gave me high frequency listening fatigue at high volume after about an hour that I never get from B&W.  
The B&W's are back up, and for now will stay there until I can afford to move up to something that is a more incremental and dramatic improvement.  
Thanks,
Eric

Embarrassing but I must correct again-I have the 685's not the 686's