Is it better to use a little more brown sugar, or less white sugar?

Use Xylitol instead: Sugar is sugar. The less, the better. I recommend replacing sugar with Xylitol. Xylitol is a naturally-occuring 5 carbon sugar, with 40% fewer calories than sugar. It looks like sugar, tastes like sugar, and is heat stable (you can cook with it). It kills bacteria in the mouth that cause tooth decay, and kills H. pylori in the stomach that cause ulcers. It does not raise blood sugar levels.