Given the apparent ability for ships to now change rank and models freely, I suggest that pirates get a major overhaul. This would include modifying passive slots, the way they look, paint schemes, new modules, special modules, and other extra features such as various ramming devices and special physical ship abilities.
They would look like a more run down and angular version of the new Ellydium ship development trees, and possibly be a golden hexagon surrounding the ship in the middle, with sharp angled branches coming off of it for the development nodes.
Because pirates are pirates, all development nodes would involve insane amounts of credits and synergy. No special resources, though each node -can- be bought for GS in place of the synergy and credits.
I highly suggest that the Sai, Grim and Phoenix get the first trees. Primarily the Sai but the others too.