I have asked Hyperion about a replacement speaker for the centre channel, and they didn't know when they would have a replacement available. The feeling I got is with the economy in the tank, that they are not entertaining any production of anything.
They would sell me a new centre channel, but I think they are just clearing shelf stock right now, and I do not get a warm and fuzzy feeling about this company lately.
Which is very sad, not only have people have invested good money, but it is also a great product (for the most part).