Differences between B&W 600 series 2 and 3?

Hello, Everyone,
You may have already covered this, but has anyone had experience with the differences between the B&W 600 series 2 and 3? I know the later 2 series are significantly different than the series 1 due primarily to the nautilus tweeter, but I haven't seen alot of discussion around the differences between 2/3. I'm mostly interested in the sound differences, so if anyone has upgraded to the 3 from the 2 Id be very interested in your opinions. Thanks!
Call Rotel of America and ask for Tim Wyatt. They are the US Distributer....He will tell you for sure.....