If you are still planning to position your speakers in the corners and close the wall, the 685s would be a backwards step, as modern B&Ws (like most speakers now) like a bit of space and will produce boom and bass overhang in that sort of set-up. If you have the space to pull them away from corners and with decent clearance from side and rear walls, they would be worth a try but I would suggest an audition to make sure they don't disappoint after your DM2s.
I do agree with Chebby that loadspeakers haven't progressed all that much. There has been a race to produce large-speaker bass from small enclosures with narrow baffles and this can be an issue if you like a natural sound without over-emphasised bass. This is one of the reasons why I love my Rega RS1s as they have been engineered for a natural sound rather than a bloated one and they are something of an exception amongst affordable speakers. The Audio Note speakers that Chebby has a wonderful if you like a natural, immersive sound (I auditioned a pair about 18 months ago), and would be well worth a try.