10 speakers is overkill unless you have a dedicated home cinema room (the big ones). Stick with a good 5.1 set now, then add two more rears when the time is right. Even a second sub is a good idea depending on room size. But those KEF will not be enough for a medium-sized lounge.
I don't have alot of room in the bedroom so perhaps I will just go for the cheaper KEF's for now. If I move into another place and put it all in the lounge I can look at some better speakers and then maybe a cheaper amp to keep the KEF's happy in the bedroom.