So i ended up taking the plunge with the Quad SC-2 Centre Channel. They're larger than the Quad SC centres (5 inch driver as opposed to the 4" in the SC) and more importantly, they will match my S5s so that the centre channel will hopefully achieve perfect synergy with the fronts.
The Quad SC-2 came out days after I got my Quad SC. Not much of a price difference between them, (just checked the prices. They are currently cheaper than what I paid for the SC !!!!) I would have preferred the bigger SC-2.
Am sure you will be happy with it but don't expect it to perform and sound like the S5's. My SC doesn't. Use the centre for music, some of the magic is gone. But it does bring in something new with the 5.1.2 playing and its a different kind of fun.