B&W 685's Vs KEF LS50

I recently picked up a Peachtree Nova 300 (an amazing integrated amp IMHO but thats another story) and am running it against B&W 685's with great results.
Q: I'm wondering if the KEF wired LS50's would be an improvement to the B&W's?
The ls50 would be an improvement in refinenement and tones,  but you may end up trading one 685 good quality for a ls50 good quality.   Like mzk says, you would get more out of the r300.
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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
I believe the LS50s are an upgrade over the Bowers 685.
I have owned the 685s and enjoyed them paired with the Peachtree 150. I now own the Kefs LS50s and they offer an incredibly focused 
soundstage and razor sharpe imaging. However the Kefs are not everyone’s cup of tea so YMMV. Everyone says the Kefs need lot of power, this is true - you have that in the PT 300. At the current price of $999 the LS50s are now quite the bargain. I suggest you buy the Kefs online from one of the dealers that offer a 60 day return policy so they have time to break in and compare them to your 685s for a period of time to actually hear what works for you.

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
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Try a Rogue Chronus Magnum integrated amp on the 4-ohm taps with real decent weighted mass speaker stands with your 685s.

Mental has it backwards... low sensitivity speakers need more power and vice versa.  Small bookshelf speakers usually are less sensitive, therefore require lots of power/ current to come alive (don’t confuse lots of power with lots of volume, that is not what I’m saying).

i just went from Kef LS50’s to the B&W 685’s.  The LS50’s are very very open sounding.  Loads of detail and imaging that is outstanding if set up properly.  They sound very good off axis as well.  Female vocals on the Passive LS50’s can be spine tingling!  The Active Versions crossed over at 80hz to a Rel T9i sub equals audio nirvana; Im sure that you can achieve similar, possibly better results with the Passives and a good sub.

The LS50’s should should go great with that peachtree.  I think that the power and sonic character of the peachtree will pair well with the LS50’s.  You might want to consider some R300’s as well.

The difference in sound between the LS50’s and the B&W685 is the difference in sound between Kef and B&W my oppinion.  The B&W’s have more sparkle and more of a smiley face eq curve; the kefs sound drier to me, more accurate, more like a studio monitor.  

I think the LS50’s are definately a step up in performance from the B&W 685 but you’ll want a sub to get the most from them.  The B&W’s have solid imaging but the LS50’s have a wider, deeper and more holographic soundstage yet it’s still well defined.  The clarity and openess the LS50’s present is audible to non audiophiles.  I had a blast introducing a 50 year old friend to hifi one Friday night.  I took my Active LS50’s and Rel T9i over to his house and we rocked music for 4 hours straight.  He went out the next day and bought a pair.  The following week when my brother heard them he also bought a pair.  
b_limo -
"i just went from Kef LS50’s to the B&W 685’s "

You had Kef LS50 and went to the B&W 685?

Just wondering...
B&W definitely different sound signature than KEF.

KEF is more neutral with uniform dispersion, B&W has very British sound with tipped up upper bass and highs and a BBC dip in the crossover region. Closest with a similar sound signature would be the new Paradigm Prestige and Persona lines. Kef is more similar in terms of sound signature to Focal or Revel, although more rolled off.
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.