The only thing it effects is how fast the compass moves in surveyor when using the cursor keys for compass movement. I prefer to have more control so my settings are compass speed set to 0 and compass movement set to Mouse. This regulates the speed based upon the distance from the mouse pointer and the compass.
Set the compass movement to keyboard and use the cursor keys to really see the effect changing the speed has on the compass but I prefer to have the cursor keys handle rotation.
William