Kirk,
Have you ever considered making the IPTC fields displayed in the Info panel editable? I ask because often I find the IPTC Info dialog too cumbersome (i.e. all the fields are displayed when I only use a few of them) and the image is too small (yes, I know you can zoom it, but that is yet another mouse click or keystroke), whereas the Info panel in the Preview dialog is customizable.
Deven