I am using Freecom 7000 on the 777, agree with Christophglex it is a good headset.
However I find it is a bit money waste for me as we do not use intercom at all and most guys only use one side of the headset and the other ear uncovered to hear each other, plus speakers from TOC to TOD so it is really abit too expensive just for that, If i get to choose again I think 3000 would be enough.
but on the other hand i also use it to fly piston planes and it works very well.
I also had Mach 1 before but I would say it is not worth buying, send back for broken wire 2 times in 3 yrs.