I was playing around in IonCross while testing ships/guns in single player.
I came across the Swarm missile pod, I mounted one. it is a worthless weapon in it's current state (damage 10/5 ). but I found it does shoot down missiles. so...
increase it's speed to ~300, it's range to ~1500, make it use ammo, and mountable as a CM? (if that's even possible). make it a "offensive CM" that's purpose is to shoot down missiles and torpedoes that are shot at you (or at someone else) plus if it were a "CM" it could be fired while charging for cruise, so it may work as an anti CD as well.
Maybe even have it sold somewhere somewhat as-is (make it use a gun/missile slot instead of torpedo, and maybe take ammo), so a fighter escort can shoot down torpedoes and missiles fired at cap ships. (an alternative to those pricey CD's)
Either way It would have to target each missile you want to shoot down, and it would still be about worthless for everything else; So if it were a "CM", mounting one would put you minus your standard CM and could leave you more vulnerable to missiles fired at you; Or if it were mounted as a gun/missile, you would lose a gun.
Normal missiles can shoot down missiles/torpedoes quite well at the moment. The swarm pod woud be better, as it fires multiple missiles, however it would create more lag on the server (more projectiles to calculate).
In a Bounty Hunter Gunship, I could easily shoot down the Battleship Isis' missiles as they slowly came towards me, with turret and missiles.
Yeah. Swarms were great weapons, in both phases. The first phase, they shot like, many missiles. Was awesome. Next, they shot one heavily powerful, insanely tracking mini razor type thing. Thing is, they lag. Lots. IF you not my comment about 82 in my sig, I say that because I could chainfire two swarm pods at any cap from about 2k away, and it was effectively a fire and forget weapon.
Ah, I remember the days when Swarms were useful... had two mounted on my bomber. I was quite the missile spammer then.
Anyway, I don't see why we need a missile specifically for shooting down other missiles and torps. The CD does that just fine, and rather inexpensively with a Wasp. Sounds like you're just suggesting a new kind of CD. Which, in its own way, isn't that bad, I suppose.