As much I love SY, I donīt think they have made not much somebody else has made before. I think they just made unique mix from the before heard elements. Here are few examples from the sixties, that could put into some SYR-release and no-one notices, it isnīt SY:
http://www.youtube.com/watch?v=EDhg6xi1qgo
http://www.youtube.com/watch?v=SYxNE3Y6uPk
http://www.youtube.com/watch?v=9ob4G...eature=related
But of course if the question is also how many have heard those and how many SY, then SY is really influental.