I've tried 225, 250, 275, and most points in between. 275F is the magic number. Every time I did 225, it took too long to break down the collagen and the brisket ended up dried out. In his newer book, he advocates for starting out at 250 for a few hours, and gradually bringing it up to 275 after that, and upwards of 285 post-wrap. The idea is that you get more smoke absorption going lower early. But 275 all the way through works just fine in my book and you get plenty of smoke.
On the WSM, I just foil the water pan empty since I have the BBQ Guru controller and don't really need a heat sink. But I put a small water pan on the grate. From there, I just run it at 275, wrap when the bark looks good and it's made it most of the way through the stall, and pull when probe tender (low 200s if I wrap).
On the stick burner, I put a grate level thermometer probe in front of the brisket with a water pan at the other end. That probe input has a high/low alarm, which I set for 315/265. Every time it hits 265, I throw another split on. It rarely gets above 290 or so. I've just learned to live with the swings. After the stall, when the bark sets up, I either wrap or foil-boat the brisket and cook until tender. But I'm shooting for an average of 275 all the way through.