Do you think eye of round pastrami would be as flavorful as pastrami made from brisket? I've bought so-called pastrami in pillow packs from the lunch meat shelves in supermarkets and they taste nothing like real pastrami. I've made eye of round roast a couple of times but have never cooked it in my smoker.
As far as USDA Prime brisket at Costco, I had this conversation with someone else here on SMF. Choice brisket is already fatty and it smokes or slow cooks into tender, moist, and delicious orgasmic goodness just fine. I think that buying a Prime beef brisket is a waste of money. I remember buying some Waygu beef patties at Trader Joe's and discovering that good ol' USDA Choice ground chuck is superior in flavor. Sometimes less is more.