Unfortunately I won't be actually making these since currently I don't have the time to go into modding (I'd love to one day tho). This was more of a general idea/suggestion to improve on the vanilla game. But why exactly do you think they would be awful? I get that Sabots are really strong so most things in comparison may seem weak, that's why it would be nice to have alternatives.
Maybe the torpedoes wouldn't have limited ammo, it'd reload one missile maybe every 25 seconds or so? So you'd have an option of taking a weaker, less reliable kinetic missile but it would be useful throughout the battle. May actually help with the ''once it runs out of Sabots it's almost useless'' problem some high-tech ships have.
The conclusion I came to when trying out various sabot alternatives is this:
You need an EMP component because the AI is far too good at just flickering shields off and making the entire anti-shield component useless, which is obviously awful in a limited ammo weapon.
The 2nd-stage direct fire component is too good because it stops PD from doing it's job, lets the missile do some weird stuff on misses or when the target switches and makes it a pure reaction game with random timing when used against the player.
So I thought, hey, why not switch around the harpoon and sabot missile styles? The result:
HE Sabots are fine. Because the default state is shields-on not reacting fast enough isn't an issue for either side. The HE damage being spread to smaller instances of damage stops it from just being basically an atropos in how it's supposed to be used and gives it some nice variable output depending on target size. Obviously tweaks to pattern, spread distance and damage could optimally position it as a more interesting missile. TLDR: Please get rid of Harpoons, Alex!
But Kinetic Harpoons either suck or are way too good. Having them be single-stage is obviously better for gameplay because now PD can do what it's supposed to do. But limited ammo in a single missile means shield flickering is far too good, so the kinetic damage has to be really high to make sure the hard-to-get shield hit actually matters. But if the kinetic damage is enough to do that, it's too good against hulls and armor anyway so it turns into a no-downside weapon. (The reason the 2nd stage of Sabots got turned from single-projectile to shotgun in the first place!)
Now your torpedo version I think falls right into that issue - it's either gonna have enough kinetic damage to make sure the rare shield hit has a big impact on combat (and be too good against hull) or the kinetic damage is so low that a small ammo pool just makes it useless and the few shield hits you do get just don't feel impactful.
One of the teasers from Alex for the next version gives us the solution though I think:
Now that scripted non-standard damage modifiers are on the table, a single-stage, possibly multi-launch (x small, decently fast missiles per trigger pull), kinetic and emp missile with low kinetic damage but a
scripted mulitiplier to shield damage could be the balanced Sabot alternative that works. That would let the missile have enough shield damage to make a hit worthwhile, without requiring it to have so much kinetic damage it starts being a ship killer. And the single-stage keeps PD viable, while the multi-missile component keeps shield flickering harder but not impossible to do - and makes it much less binary of a matter because you can partially succeed or fail at the flicker.
As a side note, ammo is a huge issue with kinetic missiles, because by definition the defense they're supposed to counter is infinite, while missiles are not (while HE missiles are targeting a finite defense - Armor and HP). One of the reasons Squalls work is the very deep ammo pool.