I've never had a problem against gunners with destro personally, and ironically you seem to have the same reactions I do when I match up against them. I try to make them waste their moves when they do in the air, or do anything to make me "chase" after them, I don't. I parry spin to the outer ring and use v-2 as a gab closer to combo them down. I see a lot of destros waste all their focus with their parry spin when that is exactly what your opponent wants. Destroyers seem like such an in your face class that being less aggressive seems counterintuitive, but keep it in mind if your being lured they want you to chase after them so they can just keep wailing on ya from afar. I agree that making a gunner might be advantageous for you and ultimately in your understanding of how to beat them, or spar with a gunner friend Good luck in your future fights =)