Eh, the most carronade centric ship was the Goldfish (aka Blenderfish) which was nerfed in various ways in 1.3.2, Eric did us the honor of going as far as nerfing Chute Vent itself to further lower its effectiveness, other than that, the Heavy carronade always benefited a lot more from different ammo types even back at 1.2 when Loch was still at 250% damage instead of 225% that it is now, it also did less damage to your gun which means gunners had an easier time repairing it, not anymore (plus very skill based cause it has no turning, which seperated the good from the bads)
Hades doesn't need gunners, Incediary is bad choice for the large clip it bears, Heatsink is still faily bad and Greased doesn't reduce arming range that much, none of them actually do. it's around 30-35 meter reduction max.
Not sure why the Light Flak needed a 300 meter arming range (it's too much IMO, 150-175 meters would be much better), lol, that makes it a pretty bad choice if anything for a multitude of reasons other than using a gunner for a light finisher is a bad idea since you have him sitting there and doing nothing till the armor is down.
/rant
Gunners still not that viable, still selectable but very niche, but not worth it most of the time and with the current Banshee and Hades, you need engineers more than ever. Opinion, of course.