I have a Nikon D800e and bought four of these Lexar Professional 1066x memory cards to use in it. I do a lot of birds-in-flight photography that requires fast shutter speeds and fast frame rates in order to capture just the right shot.
I found that these Lexar CF cards allowed my camera to clear its internal image buffer faster and capture more images in a period of burst shooting than my previous CF cards that operated slower. The difference is equivalent to a 10-20% faster frame rate for the camera.
Always go for faster CF card read/write speeds when you shoot fast moving subjects. You will be pleasantly surprised at the difference.