I use N802's for the L & R front speakers and N804's for the L & R rear surrounds. Both sets are bi-amped w/ Denon AVR-5803 receiver to drive the bass portion of each speaker (170W), with a B&K Ref 200.7 (200W) to drive the tweeter/mid portions. Incredible dynamics and detail. I originally used less power but all of these speakers really opened up after givin em the juice.
I emailed B&W to make sure it was OK and they basically said it was more likely to cause problems if the speakers were underpowered, and difficult to give them too much power. These speakers are engineered to handle serious loads, in fact it seemed like they were just waiting for it.
I say, try it, you'll like it.
Peace.