Rob, if you use those 2 cups' worth, I'm afraid you're going to oversmoke. Remember, Candy Sue won 1st in brisket at Lebanon using 1 cup of the JD pellets, total. Two foil packets had 1/3 cup each (about the amount of one of the sample packets) that she buried in the unlit charcoal to fire later during the cook, and one packet she tossed on the coals at the start of her cook.
I've done briskets with just the initial packet of pellets before, and been pleased, especially if I was feeding someone who didn't really care for a really strong smokey flavor.
Just my 2-cents... I'd go for 1 cup total in three different packets if you're a smoky kinda guy.
Keri C, smokin' on Tulsa Time