I just bought an Airrus Nano Fusion last week, and I was looking for opinions on the internet, because I really loved the rod.... I found this thread and wanted to add my opinion...
There's several differences between these 2 rods. The Nano Fusion is a little heavier, but have more overall power on the backbone. The Nrx is lighter and the components, in my opinion, are better, but there's a lot less power reserve. On the sensitivity side, I think that the Nano Fusion is better then the NRX (by a good margin), the real difference is the carbon fiber handle, it's using some sort of megaphone technology, that may be just marketing, but the feeling is really incredible, you can feel every little bump, every little touch.
Considering the price difference if you look for sensitivity, you should go for the airrus.
