I have been considering the same thing. I recently purchased the N802s and have a 250W amp which drives them pretty well, but after some discussions with my dealer I think it would be better to go with the 500W power rather than biamping dual 250W. I think the bass would benefit more from something more than 250W. Besides that, I am using the XLR connections, and my preamp doesn't have dual XLR outputs, so I'd have to get a custom Y adapter made which is also a concern - I'm not sure if that would degrade the quality of my cable connection or not - and it does change the input/output impedance between the preamp and power amp.
As Mezmo mentioned, its better to go with the 7BST or 14BST since they are designed for that power. I think in general bridging an amp raises its distortion numbers a bit so the monoblock design would be better. If you have the money, then I think your choice should be getting either the 7BST or 14BST. I think I would lean more toward the separate 7BST monoblocks, but there probably isn't much or any difference between the two 7's or one 14 - six of one or half dozen of the other...
As Mezmo mentioned, its better to go with the 7BST or 14BST since they are designed for that power. I think in general bridging an amp raises its distortion numbers a bit so the monoblock design would be better. If you have the money, then I think your choice should be getting either the 7BST or 14BST. I think I would lean more toward the separate 7BST monoblocks, but there probably isn't much or any difference between the two 7's or one 14 - six of one or half dozen of the other...