I only had one computer "synced" with my account. I've been browsing through the help forum and it seems like I might be out of luck bc Firefox sync wasn't intended to be a backup... Is this true? Is there really no way I can access the data I had synced? It must be on the firefox servers still...

You need three things to connect to an old Sync account.

1. Email address = account name
2. Password for the account
3. Sync Key / Recovery Key = without that your data is useless - as that "key" was used to encrypt your data, and since that data is useless without that 'key" you can't even download your data - it is needed to decrypt your data

IMO, too much security for "simple browser data", other than passwords.

Thanks. Ya that is a big bummer, I never knew to write down my recovery key... Maybe this should be more clearly explained in the preferences panel.

That is one of the main reasons that Mozilla came out with the new version of Sync. Too many users blew through the setup of Sync and didn't take note the message on the last setup page, as shown in the screenshot below.

Note the buttons to Print or Save ... and the note below that about "changing this will erase all data stored on the Sync server ....". IMO, a cautious person would immediately rush over here for an explanation of exactly what that message means. The only people who have ever asked about their Recovery Key (aka Sync Key) were people who didn't think to save it or print it and then found out how important it was when they needed it.