It lives! It seems Idaho Falls suddenly has a renewed interest in their sirens. I believe this is the first test in ten or fifteen years of their system, and according to the news report they want to test every three months. They have an all-Whelen system with this 3016, two 2020s, a 2016, and a 2750.
https://www.youtube.com/watch?v=WeYqvdyWwsM
It seems it was a good thing we went to record this, afterwards I called up the EMA and reported the sound and rotation issues and they made it sound like they knew nothing about them. You can hear either a 2016 or a 2750 winding down after the 3016 stops.
EDIT: The news story.