The new Firefox sync does not support my (no-)workflow: when on the Android Opera browser or the gReader RSS reader, send a tab, which is not suitable for mobile reading or demands extra attention/time, to one or more of the registered synchees, via the share functionality. How much effort has to be put to replicate that functionality? A simple Android app only for sharing URLs with desired synchees, a simple Firefox add-on for checking whether there are any new URLs fetch when a browser instance identified as synchee is created and a simple message queue on which browsers would authenticate and subscribe to incoming URLs. Should only take an eternity to implement going by my current record.
Update: With the release of Firefox 28.0.1 this is no longer the case. Another job well done! (Futurama reference, can’t remember which episode)