Depending on which slot it used there would be a reduction in hitpoints. I wouldn't be as worried about the heavy mechs as I would the ewar and assaults. But you are right in the sense that handling the balance on it would need to be done very delicately, as a module like this has the potential to be overly game changing.

Sabotage - Although I find this interesting, what attributes would you give it that would make it more desireable than ecm?  I guess if you could focus on leg slots with this module it would be a really good damage modifier. Would it negate the effects of any module? Or would it just turn off active modules?

Hacking - The only thing that comes to mind is how is this not completely broken? I guess if you limited it to only work on npc's and make it so that npc will attack the closest thing thats using any mod on you, remote reps included, it may be a valid module.