your anecdote about group sharing points out the need for a version control tool like bazaar or git... built-in.
As for privacy concerns voiced in a previous comment, I'm less concerned the mining aspect of handling my data as I am about leaks of my data. Because Google are inspecting data does not make them inherently more susceptible to leaks than services who promise to keep data private. Both are susceptible to leaks via attacks on key stores.
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