ED performance has improved by only 5% for me (2x GTX 570s) but hopefully they'll refix the Rift incompatibility from the previous set, and help resolve the microstutter encountered by some of us. How do they play for you?
http://www.nvidia.co.uk/download/driverResults.aspx/81420/en-uk
http://www.nvidia.co.uk/download/driverResults.aspx/81420/en-uk