Smoke 6 hours then bag and SV works really well but double or use a zippered bag, i cooked mine set at high temp, you always take a chance of a vac seal leaking when doing high temp make sure you use a water bath method if using a zipper bag then secure the top out of the water, done a flat like that and had the best moisture, i put in fridge overnight and finished the point on the smoker, sliced and reheated the slices the next day, outstanding
I have not done a brisket, but a chuck and top round ... typically 131 for about 50 hours is common here ... have a top round in the hot tub right now set to come out at 4pm and going to try for beef on weck.
Douglas Baldwin from a practical guide to sous vide published:
Sugar, Salt and Pepper
Cut slits in the fat cap in a crosshatch patter. Brine the brisket in a 4% salt, 3% sugar solution (40 grams salt and 30 grams sugar per liter of water) in the refrigerator for 2–3 hours. Rinse and dry brisket with paper towels.
Flavor the brisket either by smoking it for 30–60 minutes or by searing the fat cap with a blowtorch. Then vacuum seal the brisket either whole or cut into two to four pieces.
While the famed French Laundry is said to cook their brisket in a 147°F (64°C) water bath for 48 hours, I prefer to cook brisket at 176°F (80°C) for 24–36 hours. Alternatively, some like to cook brisket at 135°F (57°C) for 36–48 hours. Since some of the liquid in the bag will change phase (to gas), the bag will puff and may float to the surface. To prevent uneven cooking, the bags should be held under water using a wire rack or some other restraint.