To me, light brown sugar ("Sugar in the Raw", turbinado sugar, demerara, etc) has a distinct, but light, molasses flavor compared to white sugar, so depending on the percentage you might pick up some of that flavor. If that's not the intent, you'd probably be better off with pure white sugar. Also, the sugar should invert well before it starts to caramelize, so if a light beer is important, definitely pull the sugar off the stove before it starts to color.