If it is HT only... hmm. One of my surrounds cost 1/20 the cost of one of my mains. Im not worried about it all, that's just me. I am much more concerned with room acoustics, future treatments, better bass management, and the future purchases of pre/pro(s) for HT and/or stereo.
That being said, buying from the same brand always matches better, let alone from the same RS line.
If you listen to multi-channel music, I definitely vote to match. If only HT.... well, not as important to me, but if you got the money... why not?