Well, I didn't convert from B&Ws. I spent quite a bit of time auditioning them (600 and 700 series) because that was where I was headed before finding Axiom. At the end of the day, my ears tell me that the M60s and 703s were very close (I'd hate to have to live on the difference).
The 600 series didn't make the trip in relation to the M60s and 703s. I've actually gone back to the B&W dealer several times (using the same CD for comparison) and validated the M60 to 703 comparison. They are very similar.
As far as the M80s are concerned, for all intents and purposes, they simply play louder than the M60s with the audio being very close.
I hope this is helpful, because the question and circumstances will be difficult for finding specific experience. Hopefully, someone will be able to provide something a little more scientifically based.
