Locust was a great anti-ship weapon in 0.7.2. It was the best large missile I could mount on a Conquest, edging out even the MIRV for sheer pressure. Not necessarily against fighters, but against other ships all the way up to capitals. Notably I also had all the missile buffs. Haven't tried it in the new version yet, but I imagine it's still good at that. What it lacks to excel at this is some range.
Fighters in overwhelming numbers get problematic. My fighter fleet was once badly outgunned when a Tri-Tach bounty fielded two Astrals at the same time. It was raining Sabots and Atropos. The tactic that finally won the engagement was that I soaked up much of that firepower on a Medusa's shield, backing off and re-engaging so both the bomber wings and the Astral's Squalls were always trying to catch up with me. Infinite respawns vs. infinite flux pool. That should show you how borderline broken two Astrals with bombers are. Meanwhile a reckless attack of my remaining carriers took out one Astral, then the other.
You can't handle Atropos or Sabots very well with PD, they move too fast. Likewise with tons of Talons and their swarmers. Get efficient shields and the flux pool to dictate the engagement. Get Tac or Pulse Lasers that can deal with small threats without being distracted by PD duties. And ideally get fighters to even the odds. But with the right ships, it can be done the old-fashioned way. Low-tech loses out here. They should do very well against traditional fighters and slower missiles like Harpoons, but a mass of Atropos, Sabots; even Annihilators or Swarmers if numerous enough will overwhelm Flak PD and then they're left with inefficient shields.
If you played vs. Templars in 0.7.2, you got plenty of practice with this dealing with Clarent swarms, pretty similar to the new Atropos except twice as lethal. In the end, Burst PD and flares en masse were the best way to actually take out these missiles, coupled with efficient shields and good coverage when you could not take 'em out.