Dropbox works with the NSA to hand over customer data. You are absolutely right that something like this would go over like a turd in a punchbowl at Dropbox HQ.
Edit to add link to EFF ratings: https://www.eff.org/who-has-your-back-government-data-reques...
Dropbox was listed on PRISM documents. Are you kidding me?
tarsnap is nerdish, secure and reasonably priced for what it provides IIRC. Haven't used it though but expect someone would have yelled out here if it was bad. (In fact the only one I've seen bashing it was patio11, -because it was too cheap and too nerdish.)