Here is a link to a great avsforum discussion involving SRS Circle Surround. A guest on the discussion is a tech at SRS. The avs guys really let him have it. Moral of the story, according to SRS: Dolby is an evil monopoly, you should upgrade your receiver to handle our signal. We claim that we're better than DD 5.1, even though nobody else does.
http://www.avsforum.com/avs-vb/showthread.php?s=&threadid=290975
http://www.avsforum.com/avs-vb/showthread.php?s=&threadid=290975