features.txt

+ Designed for collaboration
* Checks for updates of beta versions (from the beta topic in the forum)
* Checks for updates of official releases (downloads.php and whatsnew.php)
+ Displays two buttons: one for the latest official release and one for the 
  latest beta release. You can update to either.
* The update buttons are always in view regardless of where you scroll the 
  changelog list.
+ Caching: The downloads from the forum page and whatsnew are cached (for up to
  one hour). Always uses the cached whatsnew copy unless the downloads page has 
  a version that isn't shown in the beta page (whatsnew is a large page).
* Beta logs and release logs are merged, then listed in sequential order by
  version number.
+ The order of listing can be reversed (ascending/descending by version number)
  by using a configuration option
* The downloaded zip files are saved (with a specific version number) so you can 
  revert to one you've downloaded before if something isn't working in a new 
  version.
* You can revert or upgrade to any version zip file that you have in the
  download folder.
* You can delete all downloaded zip files older than a version that you select.
+ Comes with a registry file useful for associating .xys files so they can be 
  placed in arbitrary folders on your computer (also comes with a file you can
  place in your XY scripts folder for convenience).

Items marked with + indicate features that I believe are unique to the OpenUpdater at the time of writing.