If forced to choose between the two, I'd go with the tabs in the title bar area. It leaves more space for the web page, though neither layout seems particularly bad.
Nailed it for people like you perhaps... but there are people (myself included) that don't want the menu bar gone. They better have a way to restore it for people like us.
I'm guessing all you will have to do to show the menu bar is press Alt, like using the Hide Menubar extension. Considering Firefox is a browser that allows endless themes, I don't know why people even care what the default is.
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If I want a menu bar-less existence, I'll use Chrome. Mozilla: please do not copy Chrome.
Mozilla: please do not copy IE.