I too, have a pair of the 45s, and absolutely love them. I primarly used them in the 757 and the MD-80. which have quiet cockpits, so I rarely, if ever, used the noise cancelling feature, but the headset itself is very comforatable, even on long flights. The sound quality is excellent, both transmitting and receiving. I highly recommend this headset.
My company provided mine, so I didn't have to pay for it, so that was a consideration, as well. All in all, a great headset.