One thing to add to the calculation is the processor speed of the camera. Shrinking the file size through compression does not materially help speed as the time to process and compress offsets the smaller amount of data.
CF cards are getting faster, but for real speed you need a setup more like the D4 - XQD cards, smaller RAW file size, and a fast processor.
My take is it is not worth the money today to get the latest and fastest CF card because your camera's processor is the limiting factor rather than write speed to the card. The move to XQD with the D4 and future cameras will enable much faster write speeds as future generations of cards are developed.