Hi Scott
There is a great demo on the NI website http://www.native-instruments.com/index.php?id=b4ii&ftu=0e9e8db65ba73af
I have uploaded an mp3 file of the B4II played on a Wersi Scala. (One of the most popular VSTs that Wersi owners load into their instruments is the B4, (It also interfaces brilliantly with the onboard Drawbars and organ controls of Wersi instruments) http://download.yousendit.com/574CF6B74B4CFDEF
I know artists that have a genuine B3 (Real Tonewheels) and they all say that the B4 is as close as it gets.
Apart from Demos I have not heard the Nord live, but if the demos are anything to go by, then it should deffinatley be worth looking at.
Hope this helps

Bill