Ballistic Champion would be a straight improvement over normal Champion, I thought we were moving away from Pirate ships being better/equal than base versions.
They should definitely be side-grades. I don't like the idea of a round of ships that are just straight-up worse than other ships and are never used by any player. D-mods already serve the gameplay purpose of giving the player weak enemies without adding to file size.
As for ballistic Champ being better, not sure I buy that. Midline's big value add is its weapon mount combinations - lots of missiles, yes, but also energy-ballistic pairings that synergize well. HIL+Squall+HVD, for example, is a killer combination on both the Champion and its big brother.
Maybe I'm weird for this but an Apogee (P) might be neat. Strip down the shielding, bolt some armour on it, convert a few of the turret mounts into ballistics and you have a Pirate exploration ship.
I like the idea of pirates having ships that a victim of pirates would likely be fielding. Keep the large energy mount and the missiles, dial down the shield efficiency, and swap the rest for ballistics, maybe taking away some of the mounts in exchange for a more aggressive ship system (jury-rigged plasma burn?), and you've got an Apogee refitted for piracy. Would be fun/dangerous as an SO ship, with weak defenses being its critical flaw.
The Shepard(P) With a system like the current Tempest, suicide drones!
Along the same lines, another great one. Shepherds are common among prospectors, pirates would gather a lot of them, and suicide drones are a natural change to make.
I'd honestly like to have a decent pirate capital. I'm fine with Atlas Mk.II still appearing more frequently, but the occasional red Onslaught or Retribution would be nice to see.
Onslaught (P) would definitely fit well. It feels weird having them be Hegemony-exclusive, given that they're an ancient, universal workhorse ship. Toss them, with high rarity, into major pirate fleets to spice up the later game raids. Not sure what I'd change about them, the Onslaught already has a wealth of different builds, and a shunted Onslaught suits pirates really well. Built-in-at-partial-cost shield shunt might be enough, though I wouldn't oppose stripping some OP and/or mounts in exchange for a fighter bay.