I currently am using the User Points Rules module to grant points (both moderated and unmoderated) to users for signing up for content using the Signup module. However, for cases where the user cancels the signup, it doesn't seem possible to remove (through another transaction) the points.
The points aren't static (i.e. 1 point per signup and thus -1 point per cancellation), but are dependent on the integer value entered for the Events content type.
Issue on d.o: https://www.drupal.org/node/2419721