John, it's all about getting enough air. If the drum is set up with a wide range of ventilation, you can cook as low or as hot as you want, depending on the weather. I got some wicked hot temps on mine when doing roadside chicken, often because I forgot to use less charcoal in the ring than when bbqing. Put a diffuser in and all bets are off, but 375* for chicken shouldn't be a problem if you have enough ventilation.
As to briskets being dry, I never had a problem, and the UDS cooks 'em so evenly so I'm rather perplexed at your brother's experience. I targeted 240* on my cheap short probe that was mounted right below the grate. Started fat down and flipped a couple of times during the cook, and then rested a couple of hours. If it wasn't for the fact that the fat in the fire overwhelms the bark I'd still be cooking briskets like that. If memory serves, I'd pull 'em off the cooker in about 10 hours, depending on size. The middle of the grate was no where close to my target temp of 240*, though.