I am using Bose A20 in my FX-3 and I'm not impressed by them. It's not that they are bad, it's that they have a bass response that is great for music but inappropriate for communications. Some aircraft microphones have a good bass response and they transmit all the low frequency engine noise. Similar low pitch background noise is picked up by some controller's microphones. This low frequency noise can make some communications almost unreadable.
The problem I have with the A20 may be partly caused by the GTR 200. It includes the intercom and is also designed to pass a music source to the headset. The GTR 200 could have been designed to provide different equalization for music and coms but it doesn't seem to have been.
If I continue to use the Bose in the FX-3 I'm going to have to find a way to cut the bass response.