XLR - is a 5 pin connector.
The 6 pin connector is also known as "LEMO" connector or plug.
To the best of my knowledge, the "LEMO" is available on some recent Light, General Aviation aircraft. Private aircraft owners can also retrofit it in their own aircraft. Believe it is a relatively simple instalation to be accomplished by a qualified engineer. This being the case for private aircraft.
Not aware of it's use in "Commercial" aircraft. By that I mean, Airbus, Boeing, Bombardier, Embraer, or similar.
Being "Commercial Air Transport" the instalation procedure would need to be certified, and that would be very costly.