Baa-Baa
I agree with almost all that Shunter has to say apart from the comments about the David Clark headsets.
After three headsets that all fell apart within 800 hours flying I went for a top of the range DC, 5000 hours later it is working just fine and my head is the same shape as it started!
A good headset is a "must have" but as with all things you will pay for quality.