Centaurus,
A risk management poser if I may sir.
You are the chief pilot of an RPT service involved in day/night operations from your aerodrome to an island community some 150 nm away. You have a fleet of six Queen Airs, a group of average but experienced pilots and a check captain.
One of your lads returns with a feathered engine, six frightened punters and a fire truck. Metallurgy tests suggest detonation. You decide to re-write your operations manual for the type and stipulate leaning procedures. In the course of your research you stumble upon Lycoming Mandatory Service Bulletin No 245-D. So whilst you are at it you decide to address the training situation with regard to simulated engine failures.
Your dilemma: do you continue using the throttle to simulate engine failures or do you opt for the mixture control as advised in the SB?
The former will ensure the safety of the crew during training but may jeopardise the safety of a planeload of passengers during a scheduled service. So how do you address the risk?
Although your PA44 may cope with throttle closures the technique is not necessarily upward compatible with more sophisticated large piston engines!