Minuses are potential batten inversion in light air, additional weight, and cost. My experience with the full length top batten which we in the Detroit fleet have had for a number of years, is that it hangs up quite often on the backstay. We have developed techniques to deal with this but I'm not sure if the addition of another full length batten would make this worse. There is no doubt in my mind that having at least a full length top batten adds longetivity to the main.