it depends on if you want pulled/shredded beef or sliced beef cooked to your degree of doneness. i have done both and i love both. the sirloin tip i smoke to 125 and then foil and rest for a few hours. you get a good variation of medium to medium rare that way. slice it thin and use as a sandwich meat or eat as is. sometimes i save a few of the more rare center pieces and slice them an inch thick and a few nights later will throw them over hot coals just enough to sear the outside and serve as steaks with grilled taters and corn.
the chuck roll you can foil after 160 to quicken cook time, i didn't but i foiled for 3 hours in a cooler to soften the bark some.
