Well, here's the results: the good news is, the Snake River brisket is, as advertised, very high quality- though not noticeably better than the prime brisket I can get at Costco for, of course, a lot less per pound. Maybe there could be some debate about this, if you are a real brisket fanatic, maybe you can discern some significant difference: I can't.
Second, after all the issues with the early part of the cook, I got it done, and it was....decent. Very good bark (as you can see). I might have even trimmed too much fat- hard to tell. I'm not Aaron Franklin, but I am sure he would know. Good smoke- I like post oak better than anything else I've used (fruitwoods, hickory). The family was happy with and practically inhaled about 2/3rds of the finished brisket, as you see from the middle picture. I also was able to send enough home with them for lunch today for 5.
Then, the bad news and the diagnosis: I've had brisket from some of the best- Franklin, LA Barbecue, Snow's, Truth, Mickelthwaite...I know what it CAN be. My flat was tasty but a bit dried out, and therefore not as tender as it could and should be. The point- the fatty part- was more moist and tender but not as good as the best. It may end up as brisket hash tonight, which is not bad.
Now, the debrief. Why was it dry? The last one I did came out pretty close to perfect, though not perhaps exactly 'Franklin-level". So remember, the night before I had started the brisket at about 325* and tamped it down to a whisper, thinking it would fall to 275-300. I NEVER thought I'd get up and find the KK nearly cold 5 hours later, at 6 AM. There are several good pitmasters, like John Mueller, who cook at 300*, so I wasn't worried about it starting off hotter than my normal 250*. The meat was still at 135* when I started it back up and brought it up to 275-300 for the rest of the cook. So why did it dry out? We don't know what temp the meat reached at maximum before falling to 135*. So it might have been up as high as 165-70, for all I know, and maybe it dried out in the second phase of cooking. I certainly wouldn't recommend a two-stage cooking method. Also, there is the matter of the "rest". I thought the brisket would finish at 3 or 3:30 and be served at 6- that would have been nearly ideal. It finished faster than I thought- about 1:30-2 and immediately went, wrapped in its butcher paper, into a very tight disposable styrofoam cooler that we had available. Next, dinner got pushed from 6 to 7:30, so the brisket stayed in the hot cooler, "resting" from 2 to 7. It was still 155* when I pulled it out to slice it, just before serving. So maybe I should have rested it less long, and maybe used a cooler which would have allowed for more heat dissipation?
It will be different next time, but any brisket cook is a difficult timing challenge. If, for example, you want to start dinner at 6PM, working backwards, you want a 2-3 hour rest, a 12-14 hour cook for a good 15-17 pound brisket. So for a perfect schedule, you'd start the brisket at 2-3 AM or so for a 6PM dinner, and you'd be taking it out to wrap around 6 hours more or less into that. Starting a cook at 2AM really doesn't work for me. If you wrap in foil to keep it moist, you can destroy the bark. So it's a challenge- I will be interested in the thoughts and suggestions from this group, which has many skilled and experienced KK cooks.