I'm using one of these:
I use the left for reverser, middle for controller and right for brakes.
On single handle trains, I use the right for controller/brakes, and leave the middle in the center of range as a guide for where coast is.
I set the upper left and right to operate the doors. Considering setting the middle button for horn/whistle.
On the other hand, I've developed the habit of tooting the horn whenever I enter a station, since operating the joystick does not keep the system "active" and the screen starts to dim out and lock after ten minutes of operation.
Love it.
