I liked SpiderOak a lot for its security, but sadly, it was never very reliable as a backup or sync service.  I spent more time troubleshooting and rebuilding databases and clearing serverside caches and so forth in 8 months there than I have in almost 5 years of other services.  And because of that, I never really felt like I could trust it as a backup.<p>Also, realize that SO is a poor substitute for Dropbox, as it&#x27;s only really a backup service.  Although it includes a sync option which works passably, the moment you access your files from a mobile device, you upload your keys to the server, and zero-knowledge goes poof.  And even if you&#x27;re willing to give that up, I&#x27;ve never met a mobile app which allowed you to access and manipulate files in the ways Dropbox does.  You can do some basic &quot;share just this file&quot; stuff, but it&#x27;s a very different product.<p>I really hope that was just because I was on it when they were growing massively due to the NSA leaks, but sadly, for me, they were a textbook example of &quot;Great idea, bad execution&quot;.