Cooking one of these should be on everyone's bucket list. Reverse sear is the way to go on these 3" thick beauties.
BTW,I used to be of the mindset that I could achieve the same results of a Slow n Sear , using charcoal baskets. I can tell you first hand that is not the case. The SnS design shields the meat while cooking indirect, even without adding water to the trough.
When searing, the SnS acts like a vortex. This was using only 50 briquettes. Never have I gotten flames this high using charcoal baskets while searing. Using the SnS I can only sear meat for maybe 30 seconds per side. Using charcoal baskets I would sear for a minute or longer.
I experimented this time by pulling the steak when the internal temp reached 125. Rested it for 10 minutes and internal only reached 131.8 degrees.
The "rib cap" sections were a perfect medium rare but the rest of the meat was a bit rare for my wife and I. Next time I will go back to pulling the meat at 128 degrees as then it will climb closer to 135 degrees, my preferred finished temp for beef.