In a nutshell, students do not manipulate twist grip in the TH-73 except for startup and shutdown. IPs “own” the twist grip for auto entry, return to flight position (full open) in the flare during a power recovery auto, and all power off wave offs.
To be a qualified 73 on-wing instructor, you also need to have completed an additional energy management training syllabus that emphasizes advanced Nr management and overspeed prevention techniques, low Nr recovery, and defensive posturing.
With just over 1300 hours in the TH-57, and now about 120 hours in the TH-73, most of which are day fam/contacts, I’ll echo
@KWpilot58 when I say I think the 73 is an excellent aircraft for autorotation training, and in some ways more forgiving than the 57. N2 overspeed is your highest risk, but as long as you’re keeping Nr under control, it’s no big deal. I certainly don’t have to worry about overtorques or iso-mount strikes anymore!