Hi James,
So the speakers I'm looking at are B&W CCM7.5 S2 or CCM682. My main speakers are B&W Diamond series, the Left/Right are 800D2 powered by a pair of 28B-SST2's, the surrounds are a pair of 802D2's powered by a pair of 7B-SST2's and my center is a HTM2-D2 powered by a 4B-SST C Series.
The CCM7.5 S2 is from B&W's top tier reference series but not the most expensive offering from that range and the CCM682 is the top speaker from the range just below their reference range, their performance range. For Atmos I can't justify the cost of the top tier in ceiling speaker from the reference range which has the diamond tweeter like my main speakers and a similar but revised mid-range, that is the CCM8.5 D. My speakers are now 2 generations old (the diamonds are currently on the D4 generation) and B&W updated their mid range driver when the D3 series was launched and that is what is found in that CCM8.5 D speaker.