Thankfully, I already have plenty of SD cards to try. SanDisk 30, 45, and 95MBs. It is the initial Compact Flash card that I need to decide upon. I heard that Nikon rates the write speed capability of the D800 as over 100MBs and the D4 as over 200MBs. Not sure why the difference but this is not the same as "up to". Real world testing is needed to see if there is noticeable camera performance increase with a card above 400x (60MBs write speed).