I just updated my database after several weeks. It occurs to me that new agencies or sub channels within agencies may have been added. Other than searching using the HP1 itself, is there a way to see the edits and changes from one DB rev to another?

Go to radioreference.com then click on Database then click on the State you are concerned about. They are color coded with the Green being the most current. After you have clicked on the State there are boxes to the right of the State that show the updates within the last 7 days and the last 24 hours. Click on the highlighted information.