HN user
Relying on a cloud service to store your data is always a risk. That is why I wrote CloudPull, my Mac app that backs up your Google account to your Mac. http://www.goldenhillsoftware.com/
I agree. Using a third party service is reasonable. The important thing is having a backup plan.
Shameless plug: This is why I wrote my app, CloudPull. CloudPull backs up your Google Docs, Calendars, and Contacts to your Mac. If for any reason you are unable to access your Google account, CloudPull ensures that you have backups of your Google data on your Mac.
More information about CloudPull is available at: http://www.goldenhillsoftware.com/