I have the 850 and have used it for about 5 years on the 756, 777, and now the Airbus. I am intending to buy and try a David and Clark DC Pro X or S because I have found that the 850 produces ever so slight distortion when compared to the simple ear piece from ops or my old custom molded ear piece. As I get older I find the importance of a clear voice is increasingly more important. I'd love to go with an ANR Bose, but I just think it's silly to have to pull it half off to make it work.
Anyways, I love my Telex for the comfort and not having to stick something in my ear, but clarity is important to me.
Anyone else use a Telex 850 that has tested this?