Caroline,
I enjoyed reading your post, and your points about how Hiebert points out how the J & P descriptors of God get morphed together. This is very thought proving, and makes me pause about how much we take our notions of God for granted. So many Christians, me included, have taken a cursory glance at scripture, and come to conclusions that are probably more based on our own "world in front of the text" than the nuances and differences that the original authors intended.
I find myself trying to apply my own traditional evaluation (Wesleyan quadrilateral - reason, scripture, experience and tradition) into theology, but you know what? I keep getting in way. Maybe that's to be expected. By Hiebert breaking out the J & P differences, I think gives us a more well rounded view of God/theology, and helps me considered what I did see before.