I guyess this might be kind of useless, but its a really short comparison between the 6.1 and the Ncode, from Jonas Bjorkmans website:
I have changed from Wilson 6.1 to Wilson Ncode, which gives me a little bit more of both speed and control.
He used to have the 6.1 and now uses that ncode everyone seems to have at the moment!
Sorry I cant be helpful, I dont play tennis
My temper is too bad