In summary, in most jurisdictions, if the flight manual says you can't leave the aircraft, rotors turning, then you can't! If the flight manual says you can, then providing you follow any instructions as regards securing the controls, it's at the pilots discretion.
Subject to what the flight manual says, then those who leave the helicopter whilst rotors turning couldn't see the problem (providing it was a flight idle, controls secured etc.), and those that don't couldn't see why you'd take the risk.
Matthew
Last edited by mdovey; 14th Jul 2015 at 20:09.