Firefox Hello is not the integration of a proprietary 3rd party service.

My problem with pocket is that I can trust Firefox Sync, because its code is open and if I were to doubt its security, I could audit it, either myself or contribute to an official audit.

I can never do that to pocket. Its a black box to me, I have no idea what they are doing with my browsing history, and therefor I can never trust it.

Its a huge sin on Mozilla's part, a company who keeps promising privacy, to sell off some of our most personal data - browser sync data - to a third party proprietary web service.