Well, it really is kinda a mute point. The signals you are sending are a digital bitstream. Pretty much impervious to noise induction anyway. But, I guess logically the optical cable would have 'less' possible noise induction of it's inherant design.
I've never heard a difference in the two cable types, nor have I heard any difference in cable quality....to a certain extent, I mean a good cable is necessary, but 100 bucks a meter is nuts.