When I bought a HP (Windows) laptop with Vista pre-installed, the manufacturer shipped a downgrade disk (1st class, overnight from the US, free of cost) so I could go back to XP.
My experience with Lion over the past month has made me crave the same service.
I'm pretty angry over all the wasted time because of bugs and most of all: the missing "Save As".
To the people that want a keyboard shortcut to duplicate files from inside applications - you can configure that yourself with the control panel Keyboard. See attached screenshot for an example.
To complement this information - the keyboard shortcut to choose "Don't Save" in a save dialog is command-backspace. You may want to use that with duplicated documents you don't want to save, since you get presented with such a dialog when closing them.