I don't see the advantage of David Clark. I got two headseats on trial. One David Clark ANR and a Pilot 79 ANR. David Clark are heavy, out-dated and not half as comfortable as the Pilot set. The ANR is activated by a simple button on the headset with mobile phone technology (50hr battery life - no external pack).
Furthermore, they were much cheaper. However, somebody can't be seen in a car unless it says Mercedes or non designer wear clothes...