I'm finding them quite swarmy as is! Between their love of fighters and those really long-lasting missiles, I'm finding PD absolutely essential to keep the skies even marginally clean.
Hello there NasaBrindle thanks for checking in again. I hope your bounty issues were solved with .96a, please let me know if it still occurs. They do have weaknesses but they are not the standard ones you may be used to and that is by design. I posted a nice writeup on tips to fight them on the forum OP that I found on reddit and in essence what you posted is the key. Thank you for the post and I hope you are enjoying the mod.
In my current game I've seen them post "please destroy a pirate base" bounties but no more faction-wide, so it hasn't been an issue, thanks!
Re: Weaknesses: They're also very weak to fast, bursty ships. I've got a phase cruiser covered in burstfire beam weapons that one-shots most Hiver ships, especially the designated "Carrier" ones. Getting in and out without being devoured by the swarm can be an art though.
I do think that their weapons may be overpriced- One of their plasma cannons is worth almost 50k if I remember correctly, which means you don't have to beat too many fleets to have a million in loot.