I think that the problem is actually that the higher firefox devs. seem to be focused on looking like chrome/opera... and keep on introducing new features that break the rest of the browser.
People don't move to chrome because of the ui(well okay, some do, most I know didn't), they moved because it was faster and less buggy.
What firefox needs is optimization/cleaning, not new features.
I will personally stay with the fox until chrome or opera allow for both real gui modification(which both opera and chrome lack) and extensions(chrome has that, or at least starting to pick up).v