Firefox certainly has a larger library of add-ons and those add-ons are more powerful than ones available from Chrome in terms of customizing the browser. The problem is that once you install all the add-ons you're accustomed to having in Chrome, Firefox slows down enough that it's not even worth it. This was my experience using FirefoxDeveloperEdition for the past month and although I miss Firefox's far superior address bar and customizability, the huge performance hit just wasn't worth it and I switched back to Chrome.