I guess it's better than nothing but 1.) it will cause pages (especially some Google properties) to deliver unoptimised versions meant for the real Firefox (or

I guess it's better than nothing but 1.) it will cause pages (especially some Google properties) to deliver unoptimised versions meant for the real Firefox (or more generally non-Chrome browsers), and 2.) don't sophisticated websites and apps anyway ignore user-agent string and directly probe through JS?