I work for a company that has 2 L4T's. One is fitted with the "high-altitude" tail-rotor, and the other with the standard 206L type. The "high-Altitude" tail-rotor sucks alot of power and you must be on the ball as it is very easy to over Tq. From the guys here who have lots of experience on this type, Nr decay when too much power is pulled is not an issue in there experience. LTA is however. Regardless of the take-off profile, which was never ideal, he could have had Nr decay due to something else, ie not setting N2 correctly.