I bi-amp my mains by removing the straps which allows you to feed each section of the passive crossover independently. Bi-amping allows me more control over the sub section of the speaker by using the right type of amp with it. If you use an integrated sub amp you can effectivly tune the sub section by being able to adjust volume, phase and bass rolloff independently of the mids and tweet section. The amp I use also allows you to high pass the signal thru to the amp supplying the upper range. My next step will be to remove the woofer passive crossover and control it completely form the sub amp.

As for biwiring I see no advantage at all unless you are stuck with a lot of wire at to small of a gauge and you want to use it up. SH's logic and explanations (numerous) are perfect in explaining this, I just don't understand the reluctance of some to see it.