The NX has a lot more features to it, you can slide the front back and the side windows come out. I personally don't care for it since if I want the roof off the roof is coming off. Our weather out in the mountains here can be every season in a single trip so I don't exactly want to leave it at home. The traditional framed tops obviously fold down but I didn't like the space all the frame or extra gear takes up. The NX has a bunch of clunky stuff to it that I really didn't want to be bothered with so when I got the trektop for the 2 door, I loved it so much I got the same thing for the 4 door.

Bonus is that since it lacks all these 'features' it comes out considerably cheaper.