Bi-Wire with two pairs of speaker cables

Not a problem.

"....I have tried this, but to my ears the only thing that improved the sound was replacing the little mettal strip-jumpers (those generally supplied with bi-wire speaker terminalss) with a quality jumper made from wire...."

williewonka,

Is there any technical reason why wire jumpers are better than good quality metal straps ? One could argue that wire jumpers are, in fact, inferior because they introduce two additional junctions where the wires are soldered or crimped to the terminations (spade lugs or banana plugs). 

Is there any technical reason why wire jumpers are better than good quality metal straps ?

If the plating or base metal was poor, there could very significant sonic effects.

Well done crimps or soldered connections are functionally one. In a crimp the metal is mashed into one with the spade.

A pair of metal strips has a quite different LCR than wire. Strips have no dielectric, so the wave travels in air rather than the dielectric. Strips are flat, so therefore have an asymmetric flux field. etc.

Don't believe any manufacturers claim as they have not test their product in your system. In addition, the evaluator does not have your ears or preferences.

Bottom line is if one sounds better, use it. If not don't.

"....If the plating or base metal was poor, there could very significant sonic effects....."  

leales.

Do you think that the designer/manufacturer of high-quality loudspeakers would knowingly use something that degrades the sound?

Poor plating or base metal also applies to spade lugs and banana plugs.

Do you think that the designer/manufacturer of high-quality loudspeakers would knowingly use something that degrades the sound?

Stuff happens.

We once got a new batch of NE5532 chips that had 10x the current draw. My company replaced 7 million Philips capacitors that did not meet the life spec. Of those replacements, several tens of thousand had to be replaced because if the bung was over the negative rail trace, it sucked out the electrolyte, shorted the buss and occasionally started a fire.