In a recent O’Reilly interview, Richard Stallman utters an anathema against software-as-a-service arrangements, calling them “non-free” and saying “you must not use it!” It would be easy to parody RMS’s style of uttering grave moralistic sonorities as though he were the Pope speaking ex-cathedra, but I’m going to resist the temptation because I think in this case his concerns are quite valid.
Richard says “If you do your computing on someone else’s server, you hand over control of your computing to whoever controls the server. It is like running binary-only software, only worse: it’s even harder for you to patch the program that’s running on someone else’s server than it is to patch a binary copy of a program running on your own computer.”
He’s quite right about this. The connotations of “free” and “non-free” are rather beside the real point, which is a pragmatic one. It can be risky to give up control of your data, and becoming dependent on a SaaS or cloud service is not something to do casually. I wouldn’t say you “must not”, that’s too moralistic for me, but I would say doing so is not wise or prudent.
In general, I don’t allow myself to rely on such services. And I have a rule: unless I can get all my data back through some sort of export or dump function in a non-obfuscated format, I won’t go there. I recommend this rule to others as well.