What version are you on?
As for being completely debugged I am not sure there is such an animal anywhere in the theme world. That being said if you use the manual update method as outlined here
you can just switch back if there are any issues.
The only things you "lose" are images you have added to the theme folders such as the header images, logo, and favicon. So you have to reupload them. All the other theme settings reside in the database.
If things are working OK then you may not need to upgrade but my suggestion as to whether or not to upgrade would be dependent on the version you are on.