Just got my D4 on Sat and have been reading manual, doing initial setup, etc. Have the XQD card in as well as 16GB CF card. Both cards were formatted in camera. When shooting, it's taking FOREVER (over 30 sec) for the image to show up on screen when both cards are in camera. Had it set to CF priority first, then changed it to the XQD card first but didn't make any difference. When I removed the CF card, it resolved the issue. The CF card is a Patriot memory 16GB card, so that might be the issue when using CF priority, but don't see how that would effect anything when the XQD card was priority. This card worked great in my D700. I've left the CF card out of the D4 for now. May try a SanDisk CF card later but thought I'd ask if anyone else had heard of this.