Is there any real combat role they fill that can't be done with conventional aircraft? I guess it's good to be able to land/launch from small areas if really needed. But how often is this a big factor or do they have a tactical advantage in dog-fights or ground attack with their vectoring? I would think this ability would make any aircraft more complex (higher maintenance), higher cost and possible safety issues. I was just wondering since the new joint fighter had to have this feature.