Version pre5 (build 34) Google docs support?

[superflexible]

Also Amazon is much faster and has a cleaner, more reliable API than Google. Google's API is really designed for sharing documents, and is barely suitable for general storage.

[FrantisekHoralek]

OK, I believe you, although I do not have experience with S3. You brought me to the idea, which solves my situation. I will do backup one time (or time to time, few times a year) manually to classical Google Docs (the price list is much more friendly), and daily and/or monthly backup to Amazon S3 via SFFS, as you recommend.