In my experience, you get a speaker which performs above its price range with the Ascend (only heard the 340SE though...) and speakers which perform below their price range with BW (heard CM, 600 & 800 lines).
I know I greatly prefer the 340SE to BW's 600 line, and given everything I've heard about the 170's, I'd be extremely surprised if it wouldn' be the same for the 170SE.
Even if I could buy 601s or 602s for 350$ new, I'd choose a pair of Ascends 170SE over them in a heartbeat... (because of my personal experience with both brands, eventhough I've never heard the 170SE)
And I'll say again, I don't think BWs are bad, just too expensive for what they offer. For example, I don't think the 602 would hold up at all against the less expensive 340SE (or the 170SE as Curtis mentioned)... But a face off against the 1000$+ CM I think would be closer and much more interesting. YMMV.