I prefer the idea from Unreal Tournament with the Redeemer weapon: Let the missile be shot down.
I had that idea orginally. Make so it has like 5000 hit points or something OR make it really interesting. EG. It has alot of hit points and the amount of hit points it has directly correlates to the amount of damage it does. EG with full hit points it does lets say 15k damage in a 250 meter radius. BUT as you make the hitpoints go lower, the damage decreases as well. IF you drop the torpedo to 0 HP, it will self destruct dealing at least minimum 1000 damage in a 300 meter radius.
But the speed needs to be nerfed to be viable BUT the manuverablty of the weapon should be increased. Its like flying a little inty and trying not to hit anything but your target kamakaise style!