I'm sure someone around here can answer this better than I, but I've never heard of it. In theory, it should add alcohol bc you're adding sugar and increasing fermentation...it would also reduce oxidition since the act of fermentation releases CO2, which pushes out oxygen.
I have reservations about this, though. Primarily why you would want to add sugar and not add more DME, if getting more alcohol is the end goal.
Also, I would be careful if you are going to bottle condition to get carbonation, adding too much sugar may not leave enough hungry yeasties to do the job properly.