Swombat,
QF settled on a Sennheiser unit for the B744. Nearest I can find is the HMEC 25 ANC headset in the A/c Spruce Catalogue for US$675.
It was chosen after an OH&S [occupational health & safety] review of flightdeck noise. The technique is to use 'one ear off' below A100 and intercom above. Works great for me, but some don't like it. Greatest drawback is that folk can enter the flightdeck behind you and you have no idea they're there.
They sell spare earpads and pad covers. The covers are a must as the pads are a plastic and you'll tend to sweat. If regularly replaced, it's no problem. QF provide spare pads, covers and batteries for those a/c not re-wired.
Summary; I'd sooner have them than not.
Hope that helps.
G'day