Whilst away recently I sent my old pair of DCs to AD Commcepts, who have converted them to ANR by replacing all the innards and adding a box with battery. I had never previously used ANR and I have to say the difference is amazing. I can now actually hear ATC! I don't know how they compare to a new set, but at £190 fitted (less if you do the fitting yourself) it seems to be a very good compromise, far cheaper than a new Bose or DC and means I get to keep using my tried and trusted old set. I think they can convert most types of headset so may be worth giving tham a call.