I've only done a couple cooks on my SJG (used an SJS previously.) I have used both sides. If it runs a little hot, then just use one side. Set it up and cook something and you'll figure it out soon enough.
Got a basket ! I have been experimenting, got another butt on now and this thing just cooks. I'm down to just starting five coals, kicking along at 275 on the side, so maybe 300 in the center, with the sweet blue apple smoke out the vent.
i use both sides. if fine tuning is needed i might shut the top vent just a bit. but as many have mentioned, experiment. i'm going to try using one side next time and see what happens.