My experience applies only to my set up, so grain of salt, etc.. My Paradigms absolutely benefited from bi-wiring. Maybe it's the connector the speakers come with between the binding posts, but bi-wiring makes a positive and very audible improvement on my speakers. Decent quality jumpers also improved my sound, but not as much as bi-wiring.
Anyone who says "never" is speaking outside their experience and/or would likely be content with coat hangers for speaker wire. They're usually the ones who think if two wires deliver the requisite voltage, they must be identical.
