I have some reservations about noise cancelling headsets, probably because I was brought up never to use intercom - we just flew around with one earpiece over and ear and conversed with each other on the flightdeck. If comms were difficult (HF for example) we would temporarily put the other earpiece on.
There are times when I now find it quite confusing as intercom seems to be used all the time and I seem to spend a lot of time adjusting the ATC/intercom sound levels, whereas with the "old" system it was much easier to differentiate between the two.
Also from an airmanship point of view there are some noises I want to hear! Noise can be a good clue or cue as to what is going on - airspeed increasing or even unusual noises from the engines etc.