bose headsets are good but I dont think worth 7-800 quids worth whatever they are charging for them now.
I used them when flying the B-200 and on 1 day the set i was using broke then got the backup headset out and the earpiece had fallen off!
.......but thats just 1 mans opinion!
On the other hand, the Sennheiser HMEC 250 that MIKECR is talking about I use for flying a turbo-prop and GA, I've had 500hrs of use from mine and think its great.
I think its just as good, its half the price, plus you get a nice little case to carry them in.
And again on the other hand, if money is no object and u want a noise cancelling headset I'd rather buy the light speed zulu than the bose, a friend let me borrow hers for a day and thought it was the best out the lot of them.