The game is built for DX9 but it is capable of being upgraded to DX11, as the developers wanted to make sure they can improve the game gradually as time goes on. PS3 version obviously is not going to get enhanced, but PC is a different beast altogether.

I doubt DX11 would fix all the problems but from what I've heard the optimization of DX11 is better than DX9 by miles. The game would definitely benefit from the switch.