Bi-amped vs. bridged to mono

What are the differences/advantages to bi-amping two amps versus bridging two amps to mono? I am pondering purchasing two Rotel RB-1080s and using them in a bi-amped configuration. Or purchasing two Bel Canto Evo 200.2 and using them in a bridged mono configuration? I am driving B&W Nautilus 804 speakers.
Seperate channels for each driver is allways best as long as the bass amp channel has enough power-if not then bridge the channels and go mono. Do veritcle bi-amp by using one amp per channel (total channel seperation and a power supply that has to deal with only one bass signal not two). Each amp has to deal with only one side of the bass which is where most of your power is needed. this also seperated the highs instead of sharing a single amp.
The EVO's bridged are the way to go. The channels are run in differential mode. So the noise floor is lowered. Not to mention the SET sound and the extra headroom you will have.
Right now I am running with 2 EVo2 amps mono in my system.
Very nice... I borrowed the second Evo from a friend. I might have to get another one now.