how does this amp handle the 80's, vp150 and qs8's?

Enough power?

I've also heard there is a way to use the extra two channel's on the 3805 to bi-amp the front speakers somehow. True? bad idea?

The 3805 should have no problem driving the 80's. Actually if you call Axiom, they often recommend Denon and HK for driving the 80's. Of course, there is also the route of using amps/tuners also, and there should be plenty of choices as well.

>>I've also heard there is a way to use the extra two channel's on the 3805 to bi-amp the front speakers somehow. True? bad idea?

This is apparently true but unless you have an electronic crossover so that only treble goes into one amp and only bass goes into the other amp you're not going to get much benefit.

We had someone from Denon (or a disty) on here recently giving some more information.

yeah I have been doing some reading on it, and it looks like your right.

Without the crossover the quality of the sound decreases and their is some hum noise. You'll get better bass to a degree anyways, but treble and everything else sacrifices.
Bottom line...not worth it.