It looks like that not all the Dell Mini 9s are same or shall I say “Dell has made an improvement”. The hinge of the old Dell Mini 9 (shown on the right) would not allow the screen to go back as the one shown on the left. The ability to go back more can provide better viewing angles in certain positions, say when you are standing.
My trusty ASUS EEE 1000H can go back a great deal, almost 160-deg or so. It is pity that the older Dell Mini 9’s hinge did not allow the users to let their screens go back as compared to the new Dell Mini 9’s hinge.
[related post on DellMini forums]