I’ve been using Chrome considerably more over the past few weeks, and with the addition of [developer-only build] extensions, Firefox may gather more dust than I expected. I just tweaked the Google Reader Checker extension to fix a weakness it has: when you visit the Google Reader site, the new-items badge notification does not update to reflect the fact that you’ve probably now read the new feed items; instead, it waits until the checking time interval expires before checking again. This was easy to fix: just one line of code put in the proper place, and now when I click the badge to read the new feeds, it erases the new-items count.
As far as why my loyalty is shifting from Firefox to Chrome, the simple fact is that Chrome gives a snappier (and thus, better) experience: opening and closing tabs is instantaneous, scrolling pages is more tightly tied to the physical action of spinning the middle mouse button, and various websites with heavy JavaScript just respond faster. If I could get the Omnibar to work exactly like the Awesomebar does in Firefox, there would likely be no going back (though, of course, Firebug wins for any web development needs!).