Well, I bought this fancy Sennheiser active noise reduction (ANR) headset to fly on our B735. After the first flight of the day I forgot to switch it off and the battery was depleted the next day.
New battery, same thing, forgot to turn it off.
So I continued to fly with the headset over one ear and no ANR which was fine.
My conclusion: Donīt bother getting a Sennheiser with ANR since both of you will need to have both ear covered. You will be in your own world and propably donīt hear the Hostie bringing you a coffee. At a certain flight level you probably take the headset off anyway.
However: In the beginning both my Co-Pilots and myself used the Sennheiser ANR and it was fantastic!You are in your own world.But for communication among each other you need to press that Intercom button all the time which I find annoying.