I've made a few briskets, and they've turned out okay... in my book. Granted, I'm picky, but I've been to pro competitions before and I know what it could taste like and that's what I'm gunning for. I'm looking for that moments where the skies part, the light beams shine through and you hear the angels sing. I haven't got their yet.
At the pro comps I've been to, just everyone of them smoke it fat side down. 1) They completely dispell the notion that with fat side up, the fat bastes the meat as it renders. They simply don't buy into that. 2) With fat side down, it acts as insulation to the major flow of heat which comes more from the bottom (to more or lesser degree depnding on your smoker) and prevents the meat from drying out.
That seems like good reasoning and the fact that these guys were winning fair amounts of money, was reason enough for me. But at the same time, fat side up or down is like arguing whether or not the PS3 is the best bd player. They'll always be room for discussion and my mind is always open.