Both Nvidia and AMD have had problems with uninstalling/reinstalling/installing over their drivers since the beginning and they still haven't figured it out yet. I always recommend doing what you have linked to, ie. uninstall then scrub everything clean using a driver cleaner such as Display Driver Uninstaller that is linked there. This generally fixes most problems that people have.
I have a 280X which is basically a 7970. You will probably have problems at dawn and sunset due to long shadows and high res shadows as well as in the countryside where everything will go to shit due to grass and the ton of shadows that they cast. With everything on, I was dropping to 20-30 fps when grass came into play. To get mostly 60 fps with dips to ~45 fps at worst while keeping as many settings up, I'm using these settings. This will be even better for you since you are vsync'ing to 50 fps so it will almost always be buttery smooth:
http://www.neogaf.com/forum/showpost.php?p=160040581&postcount=1370