definitely not a zero risk policy IMO.
backups are out of date the minute they are made. Google syncs all data at all times. Google also automatically manages version histories for the life of the document so I can go back in time minute by minute if I want. No accidental version overwrites, no user conflicts overwriting each other's work etc. Since there are no local sync copies you also avoid the risk of synchronized deletions - when a user "cleans" up a directory and ends up having the clean up synchronized over to the backup system.
Backup policies fail to be implemented (my brother is currently contracting at a high street retailers and has discovered that another team's backup system has failed to run for the last 3 months.... )
Google data is located in multiple locations, passing the location redundancy on to me.
Im afraid you are not going to convince me that using a single supplier is as risky and akin to having a single file copy. And in fact I will always argue that the data storage redundancy built into the google apps product is far better than any local solution I could develop for a reasonable cost.