Tesselation just doesn't make a difference, it takes a screen shot and a bit of careful observation to notice most of the time while in action its completely not noticeable. Turn it off, DOF is worse, for me its pretending to be a cool effect and in reality makes IQ worse, why buy £700 of graphics cards and blur out 2/3rd's of the screen real estate, most ridiculous option in a game.
Just because its an option doesn't mean its "better", I always go back to this example but soft shadows looked like utter turd in Fear, it raped performance and people enabled it, complained about the performance and complained about how it looked.
Turn off DOF, see more of the screen in detail, win win, turn off Tesselation see a higher framerate and little to no other difference.
480gtx's in sli in Metro without the "Fermi launch must kill AMD options" turned on runs pretty great, you should be averaging WAY WAY above 60fps with mins mostly above 45-50fps at a guess.
A single 5850 is something like 12-15fps min's with a 30 average, its horrible, with dof/tess on, with both off its closer to 30fps min and a 45-50fps average, completely different experience in smoothness, and looks better.
