If you already have the corn syrup, look on the list of ingredients and see if fructose is mentioned anywhere. If it's like most light corn syrups being made these days the second ingredient will be high fructose corn syrup. True corn syrup is actually just glucose, but over the years there has been a trend to include fructose as well. If this is the case for your syrup, yes, the crust will brown more. Without regard for sweetness, the conversion factor for light corn syrup is 1.3x. In other words, if your recipe calls for 10 grams of sugar, use 13 grams of light corn syrup, and 3 grams less of water. If you're measuring volumetrically (e.g. teaspoons, tablespoons), use 78% of the volume you would for granulated sugar. So if your recipe calls for 2 teaspoons of sugar, use approximately 1.5 teaspoons of light corn syrup, and approximately 0.5 teaspoon less water.