I don't see how Amon getting a light subtype hinders him. Unless, you doing a an Isis rainbow team, why is it all that important. If you're going BL Sieg or Takemina, the light sub is way more useful. The only people I can think of that would really want the dark sub would be Ookuni and Sonia. Ookuni woudln't want him that much anyway and Amon still keeps his blue primary.