Own both Ezzy and NCX and have pushed them both pretty hard, slightly different feeling sails, the Ezzy being more dynamic with dealing with gusts, NCX feels more more solid and race sail like, speed peformance NCX 'feels' faster but its NOT! both easy to gybe, water start and rig and id take either of them over a Race sail for 'real fun and peformance' any day of the week, Ezzy Cheetah is probably better in rougher bumpy/ocean water, and the construction being no mono is heaps more durable, the Ezzy also has more 'range' in the tuning, you can effectively gain a half meter in size by adjusting the tuning for light or heavy winds.
The NCX has some boom/sail positives, that mean you don't need a +210boom and you can have 1 mast to suit say a 7.5 and a 6.5... This is a Big plus in my book as it means less gear...
Hoping that the new upcoming Cheetah addresses this, because less gear is good!
Both really good sails, recommend them both.