Something that Nexus said recently has gotten me to thinking, about where to place Limitations and where to place Advantages so that everything is thoroughly covered but there are no areas of overlap (where one person is paying points for an effect and someone else has received points for that same effect). A power that has some extra effect upon a particular SFX can be accomplished by giving that power an Advantage (or perhaps partially Limiting it), or by Limiting the SFX in question.
I see/propose a pair of similar Limitations; one of them, "is thwarted by various SFX", stops it completely (this is a Disadvantage on the power, effectively), and the other, "Vulnerable to various SFX", which is still a Disadvantage of sorts but not the typical kind. A third Limitation ("produces unexpected/unintended interactions") might be helpful for those completely unanticipated cases, and would essentially be a Side Effect.
This doesn't address costing issues, of course, so the entire idea is still unhelpful when it comes to whether or not these Modifiers should have a nonzero value, but I think giving them a quick -0 rating would go some distance in satisfying the need to have every effect statted out in advance.
Thoughts?