Welcome to the forum. Hope you enjoy the hobby.
Using the 'Search' feature you can fine lots to read on any subject. Here's several pages on the CNS carburetor that might make your decision easier > http://www.google.com/cse?cx=partner...CNS&gsc.page=1
The venerable NT is hard to beat when it comes to simplicity and tuning. The 'Speed' version is basically the same carb with a little larger diameter intake throat. Either one will serve you well as opposed to the trouble prone CNS.