Rotorbee, you are right there is no real better way to train but we must never forget that a real engine failure is very unlikely to be like the practice ones.
And yes the sim is good but you do know it is coming - how many stare avidly at the engine instruments in the sim far more than you would in the real aircraft?
I agree the yaw is a good cue but more than that is the sound - your ear gets attuned to the right Nr and engine noise and it only has to change very slightly to provoke a reaction.