Howling:Angels and Paradoxes

I watched Angels Take Manhattan and I was thinking about the issue with paradoxes. Well they used a paradox to kill them in the episode, but in the novel Touched by an Angel the angels were trying to make a paradox to feed on. I started thinking about that and wouldn't the effects of a paradox on angels depend on where they stood in the situation. In Angels Take Manhattan they were directly involved and thus a paradox in that situation would be like food just disappearing out of your stomach, It would hurt. However, if they're creating a paradox that they are not directly affected by then they would be able to live off of it just as easily as zapping somebody. I just wanted to put that forward given the statements by River and the 11th Doctor in the Episode and the book. Can I get anyone else's take on this?