At least in the atom format, you can provide an article feed with both creation and modification dates. It is only the lower quality feed consumers that have a problem with this. My own software replaces any updated article with that in the current feed if the mod date changed. The only thing I find lacking is a visible notification that it got changed since yesterday so I might want to read it over again. I do agree that an indication of change severity would be wonderful. It isn't technically difficult either. Your own website I see is using Drupal, which has built-in article versioning. It wouldn't involve a lot of effort to show a redlined diff on the update.