Aside from the missing frequencies, there is no reason why the sound can not be good. I have often thought about going this route as I have speakers placed inside bookcases and I often must turn the speakers on their sides, as I do not have the bookshelf height available to allow the speakers to stand up. So, since my set-up is so compromised, would using two center channels be all that worse. Don't know for certain.
Where I have made the compromise is that I would rather have sound with some lower bass presence than have niceties like soundstage. I didn't think that center channels could do the disappearing act like well positioned monitors can, but I could be wrong.
Rich
