I confess, that apart from being tight, one of the reasons I'm not sporting an ANR headset is that I worry about hearing protection - there are plenty of frequencies outside the ANR coverage, and the passive attenuation of the X at least wasn't great.
The 'traditional' DC's, plus in noisy aircraft earplugs and turning the radio volume up work for me - though not as pretty and probably less comfy. I've alos pondered that my rather nice inner-ear-monitors I use with the ipod might go nicely under the regular headset, and they're about 40db isolation in their own right..