Warren: What you see above was done at ~230F start to finish on my Weber Smokey Mountain. IMO if you want a sear, do it to individual steaks after you've smoked the roast to medium rare. This was done for a few of mine, as you can see in the last pic.
The WSM won't get above ~270F without taking out the water tray.
My kamado grill will easily get up into the 800s and with a little coaxing I can peg the gauge way beyond 900.
... oh and this gauge reads _low_. I ruined a few pizzas before I figured that out.
I tried a few "run it at higher temp and then cool it down" with the Kamado Joe, it takes several hours to come down from 600F to 300F. Not practical for cooking the same item at both temps.
Lori: These guys have it down to a science --
https://amazingribs.com/tested-recipes/beef-and-bison-recipes/prime-rib-and-other-beef-roasts