As far as shutoffs go. Here in SOCAL we allow shutoffs on all race classes. When we fly the classes that ban shuroffs, i.e. FOX/SSR or Clown, etc., IF the pilot uses one during a race for other than a safety problem, DQ.
We got nailed in a Clown race when I had the shutoff set up too senstive, so when the airplane ballooned on takeoff into the wind, pilot reaction tripped the shutoff. It was "Sorry Charlie" for us. Needless to say for the future I re-adjusted the trip so that it would take a definite decision by the pilot to make it work.