I find that brown sugar is really relegated to darker beers like stouts and porters, and especially pumpkin ales. Though I guess, you could use light brown sugar for things as well, though I couldn't see it working well with most lighter beer styles, like cream ales, wits, hefes. You want a level of biscuity/breadiness in the beers you want that mollasses note in. Ambers would probably be could....Maybe an ipa would be interesting with it.