Nancy is correct.
All Geom bones are used for animating in FK mode. The reason for this is to minimize the amount of control bone in the rig. As Nancy stated, the extra bones that get keyed are needed for the constraint setup, to allow for seamless switching.
The only bone you need to be concerned with are the ones that are visible in the viewport window. Turning switches (poses) ON/OFF will make bones appear and disappear, depending on which mode you are in (FK/IK).