Is switching from B&W 805S to B&W CM9 a good idea?

I have the nautilus 805s book shelf speakers. I like the look of the new B&W CM9's. Is it a good idea to switch to the CM9's or should I spend a tad bit more and go with the B&W Nautilus 804's. I am using a Rotel RSX-1057 A/V receiver. Thanks