I've tried both ANR and CEPs, and I definitely prefer CEP. Better noise suppression at all frequencies, and there are no batteries to fail, and the earseals don't have to be tight. As for HEMS, I used CEP while flying HEMS for years, and if the patient is going to die because I took 15 seconds or so to get the CEPs inserted, then the patient is going to die no matter what. A few seconds makes no difference one way or the other. Trying to hurry up a takeoff is one of the most dangerous things you can do in HEMS.