This has the border scheme used in urukrama's Aeterna theme, with graphite colors and more traditional icons. The graphite color is picked to match the Rave-X Gtk theme:
http://gnome-look.org/content/show.php/RAVE+X+Colors+GTK+Theme?content=165864

I feel like this border width is ideal for visually distinguishing between windows. IMO, themes with no side borders or one-pixel borders lack usability--your eye can't easily pick out where one window ends and the next begins (unless you're using compositing with shadows).

Thanks for commenting and/or voting!