I would make sure you could demo the M1200s with a return policy. I generally have a lot of great things to say about them, but they are founded on ICEpower 1200AS modules. While they are fantastic for much low impedance performance, they are rated to a minimum 2.7 ohm load or they may thin out. Your speakers have an impedance dip under 4ohm between 100Hz-1kHz. That is one heck of a dip, and you will want to ensure proper amp pairing with it.
Also, the B&W emits a brilliant sound, such as does the Ref 6. The M1200 has some nice harmonics but is otherwise a very neutral amp. It might not be a bad idea to find an amp that has a richer tonal density to balance out the sonics with the rest of your system, otherwise it may sound too dry.