I don't know how private my Sync information is. Who can access it?
I cannot find any mention of how private the information is that sync saves on the Mozilla computers. These data would seem to be gold to a data miner.
You should publish a Privacy statement regarding off-site Sync data and under what conditions it would be released to anyone for any purpose. How soon will it be "shared" with third-party "partners" in order to enhance my "online experience"?
Your current Sync information is totally silent on this question.
Re: I don't know how private my Sync information is. Who can access it?
Data is encoded with the secret password phrase before it is uploaded to the sync server.
You connect to the sync server via a secure connection via the user name and password.
So if both passwords are not easily guessable or looked up in a word list or dictionary then you should be safe even if they know the user name.