The HIL is still pretty bad; it barely outperforms a Heavy Mauler for OP costs, yet takes a Large Energy slot... and that's just the surface numbers.
If you look at the details, it doesn't at out-perform it, when we consider that it doesn't inflict Hard Flux and that, unlike the Heavy Mauler, it's artificially gimped vs. Armor (it does a mere 16.7 damage per tick against Armor, before the Armor reduction, after the hidden Beam nerf in Settings).
There is no "hidden beam nerf" - the number there doesn't do what you think it does (and is in fact a significant -buff- over what you'd get from naive calculations).
Here, then, are the -actual- calculations for the HIL.
It does 500 DPS, typed to HE. So, before armor reduction, it does 1000 DPS against armor. Since beams tick in 1/10th of a second intervals, that's 100 damage per tick.
Now, for projectile weapons, the armor reduction calculation is: total damage = damage * damage / ( damage + armor ); let's say we're up against an Eagle, a pretty typical mid-tech cruiser with 1000 armor. So a Heavy Mauler would deal 400 * 400 / ( 400 + 1000 ) = 114 damage.
If we naively assumed that beams worked the same way, that first tick of the HIL would be doing 100 * 100 / ( 100 + 1000 ) = 9 damage. Fortunately, they don't; instead of using the per-tick damage for armor calculations, they use 50% of their DPS (and that'd be that .5 value you found in settings and made assumptions about). 50% of 1000 DPS is 500. So the actual calculation for a single tick of the HIL is 100 * 500 / ( 500 + 1000 ) = 33 damage.
Now, let's get back to that mauler comparison; the mauler fires once every second, so let's see what one second of HIL does... that's 10 ticks, 33 * 10 = 330 damage. Already much stronger than a mauler, but wait, it gets better - each of those ten ticks is stripping armor, which makes the next tick do a little bit more damage. Running the numbers out, and making some conservative assumptions along the way (i.e. always rounding damage dealt down to a whole number), it turns out that ten ticks of an HIL does a total of 369 damage against our target Eagle, more than three times the armor stripping power of the heavy mauler.