Old Akro,
That's a strange way of thinking. You don't like being unkind to the engine by cutting the mixture, but you think a simulated engine failure at 50ft is gold. Sorry mate, that's not gold but bloody stupid. You'll end up being more unkind to the engines when you end up as a smoking hole in your flat paddock. Level terrain means nothing when you lose control.
Unhinged's post debunks the theory many hold about being unkind for many engines. Regarding your turbocharged engine, pulling the throttle would have to be done gradually over many many seconds anyway not to cause damage. However, that could be your strategy if you're trying to simulate a gradual failure rather than an instant one.
There is in fact a considerable difference, in one case the engine is completely shut down & requires a restart & windmilling only assists the restart, in the other the engine is simply idling under no thrust power & will return to full power on application of the throttle.
Avgas, hopefully you've read through some of the posts after yours, which included advice from the engine manufacturer. Pulling the mixture, in most training aircraft since about 1960, does not shut down the engine at all. If the prop stops spinning, which will prevent the reapplication of fuel creating power due to no spark, there's a good chance you've lost control anyway as the speed has dropped below Vmc.
I was a member of the 'cut-the-mixture' club and would most likely do so again if I went back to multi-engine instructing. However, I armed myself with info from the manufacturers, engineers and experienced pilots about the type I was flying and didn't go into it blindly. Together with a risk vs reward strategy when it came to student training, I was never put in a dangerous situation. Maybe one day it could have come, but I significantly reduced the risks. I never simulated an engine failure below 400ft, I considered the effect of crosswinds on OEI landings (and therefore which engine to 'fail'), and never shutdown (feathered) an engine below 2500ft. Plus all failures were in day VMC.
One CASA source said to me the CAAP's claim about using the throttle was misleading and the author had spent too much time in turbine engines, forgetting what really occurred in piston engines. Before the rotten tomatoes come, this source had 5000 hours conducting such training and knew his stuff.