Hi Sisco,
I have some experience with both speakers so bear with me...
About a year ago I bought a Focal dome 2.1 system for our living room as my wife was using my rather expensive stereo set-up to watch the news and nat. geo. :)
The Focal sub is crap (sorry but there is no other way I can put it) it also looks like a vacuum cleaner :) but this is less important. Luckly, I was able to sell it quickly and I bought a Rel Quake instead - a much much better and versatile sub which cost me less than I got for the Focal.
The Focal Dome monitors are decent and fine if you want life style speakers, but they are not in the same class with the B&W 686. The B&W 600 speakers are very fine "hi-fi" speakers that are extremely good for the money. If you pair them with a Rel sub and a NAD or Rotel integrated you will have a system that will play pretty much any type of music right (of course the system will be very good also for movies).
I have started with a Rel-B&W600-NAD combo and trust me when I tell you that most systems costing 5 times more than that system can't play any type of music right, they will be more refine yes but not suited for any genre.
Consequently my advice is to sell the Focals and invest the money you get for them to buy a Rel sub and a NAD/Rotel integrated.
Finally, if you compare directly the 2.1 Focal system against the B&W 686 (without a sub) you might find the Focal system more exciting. But remember that the Focal system is a life-style system, i.e. crapy midrange (and not just that). The B&Ws, one the other hand, may not have very obvious highs or bass but have a good midrange which in the end is what really counts.
Good luck and keep us posted!
Happy new year to everyone!
Paul