On my 12-day trip I shot nearly 100GB of images on my Nikon D800E (aperture series and comparisons really add up at 35-50MB per image).
On my trip, the Lexar Professional Compact Flash and SDXC cards both worked flawlessly in my Nikon D800E.
I had some previous issues with Lexar cards on the D800E; apparently I simply had some bad cards, which Lexar replaced promptly. It does point out that before going on a trip it would be wise to thoroughly exercise/test a card, including downloading its contents, and to take several spares.
Card speed is not an academic issue for me: after dark up in the mountains with rest feeling like a priority (and camping), the last thing I want is a 20-minute download; the fast card speed means a few minutes to download, so I can get some rest for the next hard day. It also means ultra-fast response in the camera.
Notably, the SDXC card I used was only 400X, and its speed is reasonably fast, but notably slower than the 1000X CF card (Lexar has 1000X SDXC now also, but I don’t have one).
I also used some older Lexar Pro 133X cards in some of my other cameras; these were painfully slow, running about 1/5 the speed of the 1000X card.
Protecting yourself in the field — don’t erase cards
As a form of redundancy/backup, after downloading with the Lexar USB3 card reader (very fast), I did NOT erase the cards; rather I renamed the folders on the card (e.g., “2012-0817-NikonD800E-WhiteMountains-CottonwoodCanyon”), and continued to use the cards until full.
By renaming the folder on the card, then downloading to the computer, confusion is avoided as to which folders have already been downloaded, and it also helps organize the various “shoots”.
Dual slots saved me miles of hiking
The D800E used both a Lexar Professional 1000X 32GB Compact Flash card and a Lexar Professional 400X 64GB SDXC card.
I was glad I had both in the camera, because 3 miles down a canyon I realized that the CF card had filled to capacity, and the D800E was now using the SDXC card. Saved me a long and annoying hike back! (OK, so I messed up by not checking in advance and by not taking more cards, nice to have been saved a hike back)
See my comments on configuring the Nikon D800 / D800E dual card slots.