Don't know that I'd like to do it at some of the low altitudes mentioned here though -
true too
I don't practic them at low altitudes, and all my work, demo's, training for similarly tasked people etc. is in small machines that one has to cajole around at low level, for various reasons.
I do show and insist on hands on with moving into and out of one's own downwash in the downwind direction - at ten feet or so skid height, to pick up and demonstrate the incipient shudders, so to speak.
Having power is reserve is essential and demonstrating the flicking out of the incipient stage is easier at that height I've found.
All the real (drop like a stone) demos are done at plus 2000 feet from every which way, and a watchful eye by the student must initially be kept on not only the VSI, but also the altimeter. Amazing how it can flick 80 to 120 feet downwards and then stabilize. Hence the saying, don't do this below 80 feet, or ever.
I have no problem believing that the downward velocity of a much heavier machine in VRS would take much more airspace to arrest than a mere eighty feet.
May I say in relation to the below quote;
If you spend hours training for the remote possibility of engine failure
That, there is no argument that engine failures are a diminshing aspect of modern engineering.
I don't actually go for EOL's because one day it might fail, even though it is a large part of the verbal side traffic.
The main reason is because it IS a lesson in finality which couples absolute self disciplne. Therefore I reckon it demonsatrates the basic aspect of - think before you leap - and do so in a calculated fashion.