I also have the infinity grip. The three other buttons are for:
Push to talk, flip flop for the transceiver and the last button is for
advancing the checkoff list on the Vision Microvision EC100.  We modified
the EC100 by drilling into the PC circuit board and adding the parallel
switch so I would not be required to take my hand off the grip. Works great.

The autopilot dissingages whenever I touch any of the four trim switches.
This is a safety consideration because one could "Load up" the autopilot
trim and the pitch trim while under autopilot control and not know there is
a cross control load.  When you dissingage the autopilot you could have a
violent pitch or roll change which could be exciting.

Bob Smiley
N94RJ