Capital ships have flux limitations just like every other ship, sometimes even worse than other ships, because otherwise they would be too powerful. They have a lot more and bigger weapons that they can fire at greater ranges on a single target, and they are inordinately tankier than smaller ships so they can continue to fire long after smaller ships have been destroyed.
Anyway, just trust in Alex (the dev) that it's more-or-less balanced. Accept that that's the way ships are and work around the problem instead of getting frustrated by it. There are ways to make it work.
The flux cost of HBs is a balance issue. Except for flux and range, it has very good stats. Stats easily on par with and even superior to some large weapons.
Anyway, there is a lot of value to higher dps. It allows you to do more damage before your target's defensive measures can counteract you (shields, turning armor, fleeing, increase your flux, etc).
Using them on the Conquest, I typically put them into the same weapon group as non-missile and non-PD weapons, and my keys 3, 4 and 5 are all binded to Toggle Autofire instead of Select Weapon Group. That way I can turn off weapons without turning off PD, which is hella more useful than the button to turn of ALL weapons. To compensate for the higher flux drain, I do, in fact, active vent after a few shots, and continue to vent as frequently as possible. Short vents are safe enough, and combined with Resistant Flux Conduits, it essentially overdrives my flux dissipation capabilities with little risk (in most cases).
Regarding Ion Beams:
In my opinion Ion Beams are too expensive on a direct-fire ship. Flux is too important for causing damage to essentially sacrifice 200 flux for just EMP. 50 beam damage is almost nothing. Compare that to LR PD Laser which is somewhat comparable, and ask yourself if that absurd increase in flux cost is worth it. If you want more EMP, either get some Ion Cannons in the smalls or a Converted Hangar with a Xyphos wing. The range of Ion Cannon isn't too big an issue, espcially considering the drastically reduced flux cost and change to hardflux. And that heavy OP cost for a Converted Hangar is worth it. You essentially get the OP equivalent of 2x Ion Beams, 2x Burst PD, the flux dissipation those weapons use as well as whatever damage they soak, and the unknown cost of having those four weapons able to fire through friendly ships with essentially no directional blindspots (relative to the parent ship).
Other fit choices I like:
-Normal Flak Cannons for the extra range, which adds to the dps output at Heavy Blaster range, and the higher damage, making it more efficient against smaller armor but especially against hull.
-Hurricane MIRVs in the large slots. Most options available to and commonly used on Conquests aren't so great against high armor targets, and I don't need more ammo so I don't need to spend OP on another hullmod. This also diverts the normally expensive armor damage into flux-free damage, and reduces my need for anti-armor ballistics allowing me to maximize my anti-shield and anti-hull.
-Storm Needler combined with Heavy Blasters. They are both such amazingly dps dense weapons in a single slot, and the shorter range of Storm compared to other large weapons is less impactful when my Conquest's battle doctrine is getting in close anyway. The dps of Storm Needler against shields is so absurd that you open up a lot of options to yourself, too. You could grab the silly Devastator Cannon for some cross utility and make those small energy slots unnecessary (ie: free up some OP), or you could slap another Flak or Dual Flak on there, or you could double-down on the DPS with a Mjolnir or MarkIX, or or or...
-Sniper build with Gauss and Maulers, Phase Lance and small beams with Advanced Optics for some close-range DPS assist, and 4x Salamander MRM to make it easier to nail fast and/or long range targets. Sniper build also reduces the need for defensive hullmods, opening up additional options for you. Since this build also requires less focus, I like getting an Operations Center so I can improve my control over my fleet, which ends up increasing both the offensive and defensive potential of my fleet.
-LR PD Lasers are really nice on capital ships for providing super long range PD support (that doesn't friendly fire) to your fleet. (for PD purposes, LRPDL is superior to Tac Lasers).
