Are you worried the cloud will fall from the sky? Concerned someone will "adjust" your update set accidentally? Concerned you will "adjust" your update set? :)
Your hours spent staring at code is valuable! Backup your stuff and rest easy.
ServiceNow Update Sets
Use Update Sets to add your customizations to an Update Set
ServiceNow Code Backup (Single XML)
Check out this SNCWiki article about backing up your Update Set to XML:
Remember not all customizations are tracked in Update Sets. Below is list of tracked customizations:
Use an implementation or release plan to keep track of your untracked customizations. You can also export single records to xml in certain cases.