Have you any particular preference among those brands based on listening experiences? Might think about adding speakers from RSL (obviously) as well as other ID guys like Ascend and Hsu too. Another consideration instead of spreading your $1200 too thin over 5 speakers is to concentrate on the front three, even if that means going 3.1 for a while (or even better, saving up a bit more for even those or going 2.1 for a bit).