I've experimented with several different bi-amping and bi-wiring configurations utilizing different kinds of speakers, amplifiers, and source material. I also conducted a listening test while I was working at a high end audio shop, of about 100 of our 'audiophile' customers. The goal was to see how many could actually discern any differences between bi-amped, bi-wired, and normal setups, using a blind hearing test. Make a long story short:
Bi-amping -- In circumstances involving extreme demands on a receiver/amp including factors such as high volume, inefficient speaker design, underpowered or poorly designed amps, high dynamic range of source material, or extremely demanding bass reproduction, bi-amping clearly can save your bacon. Under these conditions, over 80% of our customers could repeatedly and immediately hear a definite improvement in a bi-amped system when compared to a conventional or a bi-wired hookup. It should be noted that under low volume levels and undemanding source material, the bi-amp advantage decreased sharply.
Bi-wiring -- In blind test comparisons, no one could consistently tell the difference between a conventional setup and a bi-wire setup. Interestingly, when listeners knew which setup they were hearing, over 3/4 of them claimed a definite preference for the bi-wire config vs. the regular setup, but they again could not hear any difference in a subsequent blind comparison.
I have intentionally not mentioned any brand or store names because of problems I have had in the past when I told this experience to others. I have been accused of promoting equipment, knocking equipment, being an incompetent nutjob, and all manner of other ridiculous assertions. I did it because I was curious about all the contradictory claims being made about these techniques, many of which seemed lacking a legitimate scientific basis. IMO, bi-wiring has no advantages over a conventional two wire connection, and listening tests confirm this conclusion. But some people are convinced otherwise, just as some people are positive that their system sounds much better using 10 GA speaker cable instead of 12 GA. These are just my opinions, YMMV. I do know that high-end cables and connectors are often the most profitable part of a system sale.