I use firefox sync as well, yet not with synced tabs but share singe tabs to a firefox account (PC, phone, work pc, etc.)
The next time I open firefox on the target device the tabs are opened.
And foe bookmark sync I use Tab Stash.
It's not a fancy reinvention of syncing - it just uses the bookmarks of firefox and organises them in folders, then shows them in a beautiful useful way in a single page. This page I use for my new tab page.