As a PPL I do not find myself in a position to answer most of the questions asked here, but this one is different.
Both, my wife and I used the DC-10-40 headsets. Usually, after 1-1.5h of flying my wife always complained about headaches to the point that she refused flying (she is also a PPL). On a flight to Egelsbach, Germany (nearly 3.5h) I have suffered of the same and we started to test most of the headsets that are on offer (They were lent to me by an old friend, the owner of Pilot Warehouse). My wife and I set with the headsets on our heads for hours, some were pulled off after 15-20min. (Telex Echelon 100) and some were just too expansive (Pilot ANR). We did not try any of the DC (Sennheiser were not available).
The most comfortable sets to our opinion are the Peltor 8006 being followed very closely by Pilot PA17-76 (ANR set). We bought 2 of the Peltor, they are light and comfortable. Yet one problem still remained. With sunglasses on, the right seat still complains about headaches. The drawback of Peltor headsets is that they are a bit flimsy and the built quality is not as good as the DC (or any other look alike). The result is that the passive noise reduction is also not as good as the DCs, however, they are our choice. The DCs are left at home or are given to the beck seats pax.
As a side note, I saw the Peltor being used by a KLM UK F27 crew while having a jump seat ride. That was the my first experience of using them.
I hope that it helps.
Edited for some missing words.
[This message has been edited by AC-DC (edited 28 November 2000).]