Jumper Cables - use the stock or should they be upgraded ?

The Vandersteen website has some great info under the faq portion regarding biwiring. So does Audioquest. I recommend biwiring your speakers if the manufacturer has gone to the detail to develope a high quality crossover.

As for manufacturers jumpers, I recommend replacement. Using the same cable manufacturer and exact cable construction as your speaker wire. Additionally, Nordost’s website has examples of different jumper configurations.
Google - nordost jumper cables pdf -To split or not to split -



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I agree with viridian.
Also, you can easily make your own jumpers out of the many bulk speaker cable or hook-up wires available.  Put a spade connector on one end and a banana on the other so you can attach them without interference from your speaker cables, regardless of whether your speaker cables use spades or bananas.
Finally, if you plan to keep the speakers for a long while, consider removing the binding post plate and soldering the cables to a single pair of binding posts for the best connection, then no jumpers are required.  

I have found that good quality jumpers sound much better than the stock jumper

I would use one run of the best speaker cable I could afford, and a jumpers made by the same manufacturer, rather than bi-wire cable of a lesser quality and no jumpers

I have used the Nordost  Reference Bi-Wire Jumpers and they were a major upgrade over stock jumpers... without doubt. The quality of the speakers you own... and your ears... will benifit highly.

With that said... I now bi-wire my system with identical speaker runs. My opinion is if your speakers have high resolving power...go with bi-wiring. Its a much more expensive proposition ... but the sound quality improves dramatically.  my 2 cents.