I just installed a Spendor HT with similar speakers although I use S9 for the front channels. It's good enough to convert me from a traditional 2 channel guy to a multi-channel proponent now.
I'm not a big fan of most B&W products (and there are lots of them with constant change). Nevertheless, I suspect whichever speaker you like in 2 channel, you will prefer in multi channel too. Not sure what the individual above is talking about with regard to the S series versus Classic line. To me, there is no contest, especially when utilized in a HT. The S series are superior in almost every way (especially the S5, S8, and S9). I can't see anyone using the Classic line for HT - they don't even have a center channel to match the drivers of the Classic line.
Among other things, Spendor get the vocals right and excel throughout the midrange like few other speakers. That's really what you want in a HT setup where a sub is usually utilized. You also don't want a "hot treble" speaker that is erroneously recommended by some for HT. They may sound attractive during brief demos of HT sound effects, but it doesn't take long to tire of that. You can also forget about playing multi-channel music only on a HT designed to dazzle during special effects.