What do you have that you want to hide from the NSA?
If you have to hide it, you shouldn't be doing it.
Joking! As if the US NSA and "Surveillance State" are trustworthy... Not!
Like you, I just assume that Amazon, Google, Dropbox, Skydrive all have "backdoors" where they will turn over your data, without a warrant, and without your knowledge, to any US government organization that asks, for any reason, and at any time.
Right now, I assume that MLO's cloud sync is similarly compromised, and that NSA, FBI, CIA, Mossad, MI6, etc., have only but to ask, and it will be given.
Based on past history, the masters they serve may or may not have lawful intentions in the public interest when accessing people's private data.
Having an FTP sync to a private, encrypted-with-no-back-doors data storage option is an appealing feature.