I can see that accuracy isn't too critical, but it feels like it gets beaten out by the light dual AC pretty badly then, since it's more efficient and almost the same DPS for less OP.
And the light autocannon is less damage, but the extra space for vents makes it functionally more flux efficient if you're really scrimping on OP.
And although the Arbalest does do high damage per shot, which I didn't consider, it's still not too effective on armor except against frigates and fighters where the accuracy really starts kicking in. The railgun on the other hand is actually pretty effective against fighters even at long range.
I guess I'm feeling like the options are:
Budget anti-shield, rather have light AC
Plan on fighting closer in or larger targets, rather have light dual AC
Plan on larger targets at long range, probably worth the heavy AC? Though maybe I'm iffy on that one too.
Want something that can double as anti-fighter and less odds of missing frigates at relatively little loss in efficiency (after adding a vent it's .75 f/d vs .84 - if you miss 1 in 10 shots they actually even out in efficiency.
Also I guess I'm way off on the HE/kinetic. I thought you usually wanted to put HE in larger slots because more damage/shot is helpful on armor. In small slots you have the Heavy Mortar (which is fine, but very much a budget weapon) and the LAG which has a rather low damage a shot that'll be pretty ineffective on heavy armor. Where the medium slots give weapons that are much, much stronger against cruiser armor.
Not always of course, if you want to shoot frigates mainly or something and you don't want to be at 500 or less range the LAG is probably better than missing with the heavy mortar or spending twice the OP for 2/3 the dps in the heavy mauler, but as a general trend at least I tend to put kinetic in small and HE in mid instead of the other way around, I thought.
Fair enough that it's meant to be a 'meh' weapon. I do think the Heavy Mortar at least has a little bit more claim to usage though since it's actually pretty high DPS HE, at ~3x the light mortar, almost twice the mauler, and over 50% more than the LAG.
In particular if you plan on fighting around 700 range so that you don't want the chaingun and it's not worth paying more for the mauler, I think it holds up pretty well - the LAG is for smaller targets, the heavy mortar is for larger, and the light mortar is if you're desperate for OP and basically just want a backup anti-armor weapon for when your missiles run out or something.