I wouldn't worry too much -- if you look at the before/after pictures in this link (you can slide it to show difference between DX9 and DX11), it doesn't look THAT different. Mostly, as Gilraen said, it seems just extra graphical stuff and not really texture upgrades or anything? Not sure myself, just going off the article and the pictures. I have a PC that can play the game in DX11 at Extremely High but I would still be satisfied with just the DX9 even if I couldn't, the difference seems so small when you actually compare them side by side (or slider).

http://www.geforce.com/whats-new/art...ward-benchmark