This was AWESOME.
OK, here's the rundown and pictures.
Here are the seasoned steaks. There's a bit too much seasoning on them; I wiped them off with a paper towel before grilling. Still, you get an idea of the size of the cook.
On the Egg, at about 250*. This was at the turn. I was experiencing "temperature rebound" the whole cook, but it didn't seem to matter much. Swings were from 210 to 300. Yeah, that's an onion holding the oven probe. We were out of potatoes. This step took a while, even with the meat starting at room temp; maybe 15 minutes. I pulled them when the internal temp hit 115*.
Boppin' the Egg up. Steaks are off to the side, on a platter. Notice how far off the thermometer is on the Egg, about 5%.
Steaks on the fire. Booyah. MAYBE 2 minutes a side. Turned then at 122*, pulled at 130*.
How easy was this? Pretty damn easy. The meat was literally fork tender, it cut like an omelet. Tenderloin is pretty tender anyhow; this really highlighted the cut's strength. For me, if it's easy and the food tastes good, there's nothing else to consider. I'm doing all my steaks this way from now on.