Interesting. Opposite of what I do. I do not go for St 9, either side of throat. Especially not with older ukes. I'd be afraid to use it in the hospital too because of the danger, and that it would look like a very bad assault on the video cameras.
I have done many KO in the dojo, (never in the hospital), with TW 17 however. On the receiving end, I don't let people hit me hard or with any intent in St 9 but I do let people practice what they want on TW 17 behind the ear.
I shall have to think about this and wonder if my avoidance of St 9 in practice is too cautious. Certainly, TW 17 by comparision, seems pretty good for practice.
The older I get, the better I was!