There was a review of ANR and non-ANR headsets in Flyer some months ago. You might be able to backorder that issue. It makes for interesting reading.
They were pleased with the Bose-X with the only remark that if you run the batteries flat, the passive noise reduction is virtually nonexistent. Not a problem if you've got the panel wired for them of course.
We've got two Robin Ecoflyers at our club with Bose-Xs in them as standard. I've flown them a few times - brilliant. Both the plane and the headset. We do have a few headsets that are broken now. Not really surprising since these planes do 700 hours or more a year, in a club/school environment.
The big surprise though of the whole Flyer review was the DIY ANR kit which you could buy over the internet for a relatively low price, and use it to upgrade your own non-ANR headset to ANR if you're handy with a soldering iron. I wanted to do that myself but unfortunately my headset is not on the "supported" list and queries to their sales people have so far gone unanswered.
Oh, and there's also an in-ear "head"set with ANR. Due to the physical characteristics they could not test it objectively but the subjective opinion was that it was very good too. And comparatively cheap.