FYI re comments directly fom a couple of heavyweights in upper range cables in the industry: CHORD and NORDOST
CHORD (from their website)
Bye Bye Bi-wire?
We have taken the decision to discontinue our range of dedicated bi-wire cables. The reason being, that in the vast majority of cases we believe that the best, and more importantly the most musical performance is obtained by using the best quality single wire speaker cable that falls within your budget, rather than a bi-wire cable of the same cost.
As an example: - instead of using a set of bi-wire Rumour 4, try the heavier gauge conductors of Odyssey 2, which will bring definition, detail and dynamics and most important of all, a greater sense of musical coherence - all of which will lead to a more involving and immersive musical experience.
We believe that the majority of hi-fi systems will perform at their most coherent best when single wired. There are of course exceptions to the rule and we are very happy to build bi-wire sets of speaker cable using two sets of single wire cable. The typical termination for these would be both sets of cables connected to one pair of banana plugs at the amplifier end and two pairs of banana plugs at the speaker end. These sets can be produced to order for those systems where bi-wiring is definitely the better option. Email us for more info.
http://www.chord.co.uk/products.php?pg=242
NORDOST (from their website)
Many modern speakers offer a split bi- or tri-wirable crossover configuration, fed by multiple sets of terminals on the rear panel. Properly executed, there is no doubt that a bi- or tri-wirable crossover can indeed enhance speaker performance, but this requires groundup
design and far too many companies simply split a conventional crossover after the fact, in an attempt to meet the demands of fashion over sound quality
http://www.nordost.com/default/downloads/NorseJumperinstructions.pdf
The Dos and DonÂts of Bi-Wiring (in that same NORDOST article)
ItÂs easy enough to establish whether your speakers will benefit from bi or tri-wiring, or not  just suck it and see. Any competent dealer should be equipped to demonstrate the difference, but there are a number of things to take into account:
 Always use the same cable to feed each leg of the crossover.
 Only use the best cable that you can; one run of cable will invariably
sound better than two runs at half the price.
 Many speakers sound better bi-wired simply because the supplied links are sonically inadequate. The metal plates or wire jumpers might not seem like they have a big effect, but they do. So whilst a speaker might sound better bi-wired than with its own jumpers in place, itÂs a fair bet that the same cables wired in a shotgun configuration (or
all wired to the bass terminals) and used in conjunction with purpose built links, like the Norse Jumpers, will offer better performance still.
 Just because your speaker offers multiple input cabling doesnÂt mean that bi- or tri-wiring will necessarily produce better results.
Optimal Bi-Wiring
Even if your speakers do sound better bi-wired, often the best route to optimum performance will involve a period of single-wired operation (thatÂll be while you are saving up for a second run of really good speaker cable).
So, how should you set about cabling your speakers?
 Use a single run of the best cable you can afford.
 Use a set of matching bi-wire jumpers constructed using the same cable or cable technology as your main speaker wires.
 Apply normal housekeeping procedures to your jumpers as well as your main cables. That means running them in, cleaning the connectors, treating them with ECO3 and fi nally making sure that spade connections are securely clamped down with the correct socket wrench. Also, make sure that you check phase integrity (red to red, black to black) and directionality when installing.