rjsquirrel -
Thanks for the advice, it's always welcome, if somewhat confused this time. I recommend you stop believing the writing on the box (-40 dba?) and listen to what flipcelia says about actual reduction.
I maintain that the implied point of this very important thread from flipcelia is how to cope with human performance reduction, stress and long-term hearing loss due to extended exposure to excessive noise; otherwise why should we concerned with it?
Esso's figures would be useful if available as they relate to this particular aircraft. When you know the characteristics and frequencies of the multitude of noises then you can select an ANR headset that matches that signature.
MD900 Explorer is correct, Bose sets are good. Some of the guys in Macau are using them, perhaps they would give advice. whether Bose covers the requirement.