First of all, have a list of all the authors who have written anything in the document. Perhaps put this along with document statistics, which bear word count, character count, number of lines, etc.? The ability to restore authorship colors is a good idea as for longer things, because people like to know who wrote what, and perhaps compliment on their work in that area. The fact that just about anyone can disable authorship colors for everyone is not good, and can confuse people while working on it.