Surely this is down to the pilot. I was at an event where two helicopters were giving pleasure rides to children. One pilot insisted stopping the rotors before swapping passengers (he was the one I was helping) the other did every swap "hot". Both were R44's so the dangers were perhaps less as the rotors are pretty high off the ground. They were certainly less than when a convential SEP was being used, but theose guys all stopped the engines first.