I thought my DC 13.4 was pretty good till the Stapleford mod was done. For an old and decrepit person like me, it made a quite amazing improvement in readability of the comms I was trying to hear.
It's so good that when the battery ran flat in flight, I was seriously tempted to land for a replacement. I now keep a spare in the flight bag.
I tried one other ANR headset, and couldn't tell any difference. I'd had the DC for years, so the mod was the obvious choice. If I hadn't had a headset at all, I might have done more analysis.
Everyone I know who's had the Stapleford mod has been delighted by it.
The "auto off" is a useful addition, and saves flat batteries. I'm a disinterested party in the ANR mod, but have a vested interest in the auto-off: I designed it for Richard.