I've been fighting buying a pair of ANR headsets for a few years now. One, because I'm cheap and two, because I still fly with the same pair of David Clarks Dad and I flew with 30 years ago, so there's a fair degree of sentimental attachment.
I did however fly with a pair of flight com Zulus the other day as well as borrow a set of flightcoms from David Read last summer on the way to Oshkosh. In short I got hooked so last night I installed the Headsets Inc. ANR retrofit fit in my old DC's and I have to say it's a winner! Basically you gut the innards of your existing headset (just the audio side, the mic stays intact) and replace them with new components supplied in the kit. It was about a 30 min job and at $149 the price is right! In fact one could buy an old "out of date" set of DC's and the kit and come out under $200 for basically a new ANR headset.
Here's the link in case anyone is interested.
http://www.headsetsinc.com/