I have one of these too, in a DC 10-40, and it's brilliant. I use a rechargeable NiMH PP3-style battery and it lasts about 6-7 hours in a Yak-52, about 14 hours in a PA-28. My Yak instructor, Ian Auston, uses the same and he swears by his too. Took me only a couple of hours to install myself, and I haven't done any soldering for about 15 years. There are people around who will install them for you, more neatly than I managed myself, but mine works fine. With a good second-hand 10-40, you end up with a high quality active headset for about the cost of a good new passive one.
You do need the proper DC gel ear seals, though.
However, very impressive too was the Adams Aviation ANC conversion kit for David Clark headsets - it works much better than it has any right to!