I have been using the Sennheiser HMEC 25 KA for about a year now. The differences from a non ANR headset are very noticeable and I could not be persuaded to return to the airline issued headset now.
The major benefits that are immediately apparent are that you can now turn down all the volume levels on your comms control box, ATC become clear although not always logical and background noise is virtually eliminated.
I would agree that cup pressure on the arms of sunglasses can be mildly annoying.
Long term benefits are more difficult to judge but I'm not prepared to risk hearing loss for such a reasonable investment - and the capital investment is tax deductible so it becomes even more affordable.
Looker