I have done the rollercoaster in the sim a couple of times. It's an interesting maneuver. Some points that I kept in the back of my mind:
* from a pilot perspective, you still have elevator, the aircraft is under control when trim runaways are dealt with without too much hesitation.
* from a pilot perspective, the rollercoaster is easy to do in a simulator environment but there is an absolute lack of physical senses (g-forces created in the pull out, or 0g at the top)
* from a cabin perspective, it seems an outrageous maneuver knowing cabin attendants might have been walking around pushing trolleys, especially knowing you are now pretty much letting go of the elevator and that might result in 0 or negative g. Meaning you are sending the trolleys and the cabin attendants, together with everybody that has no seatbelt on, into the air.
The maneuver is a theoretical solution to a "might come with broken bones and possibly necks as well" reality.
So if you want to focus on the rollercoaster in a training syllabus, I would at least double the amount of time working on the stab trim runaway scenario. Avoidance creates much bigger safety than having to correct afterwards.