For me, too, it was a close call. There were several tracks where it could have gone either way. My very first impression (under 10 seconds) was the M3. After that some tracks went one way, some went the other. It boiled down to a female voice on a David Benoit/Russ Freeman track that was in front and more 3 dimensional with the B&W (and as John said, more sibilant - but with that more natural), but fell back and was a bit more flat with the M3. I also played track 1 of Classic YoYo (Bach) - Believe it or not, to me it was too clean on the M3 - if that's possible. It sounded better, but less natural. so the nod went to the B&W. As John said, for a fifth the price, there's NO question which I'd purchase; the M3.
Scott
