Combine vinegar, 2 teaspoons sugar, and lemon juice in heavy small saucepan. Stir over medium heat until sugar dissolves. Boil until syrup is reduced to scant 1/4 cup, about 3 minutes. Transfer to small bowl; cool completely. (Can be made 2 days ahead. Cover and refrigerate.) Combine mascarpone, cream, vanilla, and 2 tablespoons sugar in medium bowl. Whisk until thick soft peaks form. Cover and refrigerate up to 4 hours. Combine berries and remaining 2 tablespoons sugar in large bowl; drizzle with balsamic syrup and toss to blend. Let stand 30 minutes, stirring occasionally. Divide berries and syrup among 6 goblets. Top with mascarpone mixture. *Italian cream cheese, available at Italian markets and many supermarkets.