I'm thinking of getting rid of the Healing Effect as a distinct thing, and instead giving each of the Attack Effects (Affliction, Damage, Nullify, and Weaken) an Extra that inverts what they do: Affliction treats illnesses, Damage heals injuries, Nullify grants powers, and Weaken strengthens traits. With the possible exception of Nullify, I see these as +0 Extras: they don't actually change the cost, they just invert the effect. Nullify's inversion might require a higher cost, as granting powers to others is potentially more useful than nullifying them — or it might just be that Nullify doesn't have an inverse.
I'm also thinking of combining Growth and Shrinking into a single Size Control Effect, with each rank being dedicated to either growth or shrinking. They're thematic inversions of each other, and are often taken by the same character (Hank Pym, for instance; or Shrinking Violet/Leviathan from the 90s Legion of Superheroes).