I just switched to Firefox from chrome out of political reasons only. I feel dirty using chrome. Sadly I really prefer the look and feel when it comes to tabs in chrome. Other than that im very happy with the experience of Firefox. Good work.
1. Firefox has a box highlite on active tab. Chrome looks like a proper binder tab just extending from the tool-/addressbar background. So much slicker. The bottom part of the highlight box doesnt have to be rendered cause it serves no purpose => less busy UI.
2. There is no clear separation between tabs in firefox.
3. Stop rendering tab name if its not even readable. With max width 50 i just see a gradient on first letter. Why even render the text? => less busy UI.
4. Make it possible to hide the tab list arrows when more tabs, than fits the screen, are open.
...I'd say you can just copy the look and feel from chrome. "The best artist steel" =D