advantage or disadvantage going biwire vs single

From my limited knowledge and perceptions, here are some advantages of biwiring.
1. The larger magnetic fields created by the bass signals don't modulate that of the high-frequency circuit.
2. Especially with a 3-way system (or at least one with a low--below, say, 1KHz--crossover), one can use lots of less-expensive conductors to optimize damping factor (= definition and control) of the bass system.
3. With either crossover, one can still spend less money for the optimum combinations of conductors to achieve the quality one wants. For instance, one can use quite-expensive-but-smaller-gage super-high-quality conductors (such as AudioQuest's KE-4, a 2-pairs, all-silver cable) for the tweeters while using a larger-gage, less-expensive cable (such as AQ's CV-6) on the bass/midrange.

Most of the advantages of biwiring can be achieved by single-biwiring, ie using the various conductors of a single cable for the 2 parts of the speaker.

I just bought a trio of premium AQ cable for my fronts. For the Aerial CC3B centerchannel 3-way speaker, I used inexpensive-but-high-gage Type 6 on the woofer and KE-6 (3 pairs of silver plus the DBS system) on the midrange/treble. For my 2-way (high-crossover) Kindel PLS-As, I used KE-4 (2 pairs of silver) on the trebel and KE-6 on the bass/midrange.

My system has never sounded better, with sweet, clean, detailed treble and midrange and great bass energy and control. BTW, I was using quite-good AQ cable previously. LOVE those silver conductors!

I found and lost an article which described the pros and cons and theory behind biwiring which prompted me to un biwire my new tyler custom linwoods for a test.

The result is that the sound isn't as tight, but its much fuller, richer, better imaging and better bass. For these speakers, with a longer wire run, biwiring was a mistake.

Of course in my den, I have some tyler reference monitors which I think sound better biwired.

http://www.sonicdesign.se/biwire.html

A bit late chiming in here, but I just defeated the bi-wire provision on my speakers, and to me the sound is noticeably smoother, fuller, and more coherent. I've only listened to three record sides since doing it, so it could just be the psychoacoustic effect by which "changed" is oft initially perceived as "improved". We'll see.

I realize that my brief description of the 'new' sound also could be read as evidence of rolled off treble, but I don't think that's the case here. My system at times shows some glare or brightness, but I think this is more in the mid to upper midrange than the treble, which could put it somewhere in the crossover range of my speakers (somewhere around 2.5-3 kHz). It seems reasonable that defeating the speakers' bi-wire capability could affect this frequency region.