I have no idea how you're going to handle implementing ships, but I've heard that they're going to be customizable to a certain degree. For the sake of variety I would separate how a ship looks from how it performs. People are going to optimize, and unless you're planning on enough variety in roles to make even opposing fleets of minmaxers visually distinctive, making how a ship looks a matter of taste would improve the visual appeal of the game, and make taking a closer look at a new enemy worthwhile nearly every time. Just my two cents.