Please educate me: I am a Chrome user and I do rely on browser syncing my tabs and some passwords.

I know that Firefox also has a syncing feature ("Sign into Firefox", "Continue to Firefox Sync").

My problem is that I don't trust Mozilla's ability to keep this data secure. I believe that sooner or later they are going to get hacked, and that data will leak. The same might happen to Google, but I also believe that no other company has the degree of expertise of Google to protect that data.

Am I wrong in this assumption? Does Firefox Sync end-to-end encrypt the data, without knowing the key, like Google's Sync Passphrase feature?

What are your experiences with Firefox Sync? Does it work just as good as Chrome's, or even better?