There should be two types of pest controls; suppression(for lack of a better word), and pulse based.

The suppression one should be like the current ones, except perhaps a bit less elec-intensive; they run constantly whenever a fire or other parasite is present, and doesn't really make them go away, but prevents them from expanding too much naturally.

The Pulse ones should take large amounts of elec regardless of whether there are parasites on board or not, but clean out the parasites very quickly when equipped.

That way, parasites would become FAR more of a tactical thing than otherwise. The trouble with this is that it would become too easy to notice when there are parasites on your ship, and anyone with a pulse based system would remain essentially immune, just like right now. So I think that parasites should not actually show up in your hull at all! It's not like you've got a running inventory on them or something, so I think that they should be invisible and drain shields or whatever in a very unobtrusive way, so you have to actually be active in trying to get rid of whatever has hitched a ride onto your ship.

I think that would make the whole business a lot more interesting than it currently is.

You are contradicting yourself, because if there are exterminators in the picture, then that will work as the cap/limit.

MCing in pvp will get you destroyed anyway if you're playing against reasonable competent players.

Jiraque is the exception to the destroyed part.
LC is the exception to the competent part.

I never understood what the problem was with the old system, all you had to do was use exterms and you were fine, yes you had to remember to use them.