Pit beef is usually made from some cut from the round, and grilled over an open pit. It is not low and slow. And is sliced thin, rare or medium rare (or to order). You can make something pretty similar (probably even better) low and slow, and smoked on the SI. The round has very little fat, and will not become tender from low and slow cooking. It must be sliced very thin to be tender. Brisket is completely different. Brisket is a tough cut, with a lot of fat and connective tissue (which means big flavor). It needs low and slow to break the connective tissue and collagen down into gelatin, which gives brisket it's lip-smacking juiciness. Brisket is cooked well beyond being pink in the middle.
