Do This, was in reference to your Billy Wall cool down method, which I have also heard about from him.
I think there would be a big difference in yours cooling down from a WSM or UDS too. With a WSM, it is nigh impossible to shut down without some air getting in, making for a sooty result I would guess. That is why I wondered if the Weber option you mentioned was removing the middle section and lid off of the lower section to let it cool. A UDS would be easier, just shut the intakes (if they are ball valves) and cap the exhaust, but I still wonder if while hte fire chokes it would produce sooty flavors. I think remvoing any additional smoke is key (besides the obvious cutting off the heat), and in a unit like UDS or WSM, you would need to separate the fire from the unit completely I would imagine.
For this to work best I am imagining a slow cool down sounds like it is the magic, I could be wrong. I think I misunderstood you in that you were talking with a brethren who was testing how to do your cooldown method on a weber, not that they had mentioned trying it themselves and you were mentioning that. So I thought you knew more about what they were trying.