Haha, the number of times I've killed myself with those stupid things...
Infyrnos are fun as all get-out to use, in Derelict, the "oh crap" mission (you know what I'm talking about), I sat by the fighterbay with a bank of Infyrnos taking out entire bomber wings in an instant.
I'm thinking of making an Infyrno II missile that has a slow lock-on, fairly crappy (but present) maneuvering, and it detonates about 200m short of the target, spraying explosives forward in a cone. Kind of like a claymore with rabies, mostly intended as a delicious anti-bomber tool.