Garfish and I are in general agreement on this topic, although my own experience is that the "knee" in the incremental improvement curve may be lower than the #2 cable in a company's product line. As with nearly all high-end audio, you pay more -- typically a LOT more -- to gain that last bit of improvement.
Generally Speaking
Okay, stick with me because no matter how many times I rewrite this it still sounds stupid. Lets say I'm looking at "Company X" and they offer four different speaker cables, lets call them A, B, C, and D (A being the best). "A" cost 1500.00, and "B" costs 800.00. Generally speaking is it better to go with "A" or have "B" bi-wired with the result that both sets now cost 1500.00? I know something like this must have been posted before, but 1) I can't find it, and 2)this might give new members a chance to post(no one likes posting on a dead thread). Thank you all in advance.