From what I can gather, the idea is on a pit that draws well enough you can close the damper enough to slow down the draw (thus not allowing all that stagnant heat to rush out with a higher draft), while still having enough draw to keep the fire lit. I'd imagine it lowers the temp of the pit more too, which is maybe how you can get away with much larger splits that way? My brother has a much cheaper offset, he's been trying it that way and claims it's cooking his food more evenly with more smoke flavor. There's been times he's had too dirty of smoke on his brisket, and other times it's been perfect. Whereas, on the Franklin "it just works" by default. I'm not needing to worry about dirty smoke because even with visible white smoke at times it never comes out dirty or acrid, and the color seems even throughout. It cooks my pork butts in around 6-8 hours, and briskets in around 12-14 (if I wrap later on in the cook)
However, that's not to say I'm always going to cook one way, I'm really trying to see how I can play around with different levels of draft on that thing to do what I want.