This extension alone is sufficient justification to shift to Firefox.

Hey! So I finally felt inspire and made a demo of my Firefox userchrome.css and Tree Style Tabs customization and CSS on my Github here [1]. It makes it so that the Tree style tabs expand and contract over the page, showing just the favicon and number of sub-tabs when contracted, along with a few other things, like reducing border sizes and adding better indication for sound in a tab. It's pretty nifty I think; I hope someone finds it to their liking. :)

https://github.com/jessebeard/firefox_settings

I wish tab groups to be implemented natively. Or that extensions can manage the tab bar instead of using a sidebar. That’s the best experience we can get so far, but it does not feel right to me.