I've just purchased and today played a walk-on with my NT11. I'm very impressed. No sticky bolt, exceptional gas use and very quiet. I also have a proto reflex rail and like that was expecting some drop off after rapid strings of shots on the NT. Not a chance, this bolt technology is such an improvement.
I'm a long time Bob Long Timmy owner and after watching TechPB's web casts were he highly rates the NT for its ergonomics, decided to try and am so glad I did.