The ONLY reason I still use Firefox is tagged bookmarks. Every time I use Chrome to test something I'm reminded how much of a turtle-pig is Firefox. Despite claimed improvements in Firefox's use of memory and processor, Chrome is noticeably better in both these areas. I still have to restart Firefox to reclaim leaked memory; after the restart, with the same tabs open, I've reclaimed gobs of memory.
I would move instantly to Chrome if the company that gave us tags in gmail would just do the same for bookmarks in Chrome.