I tested the 64GB card against Lexar Professional 32GB 133X SDHC card for speed in the Fuji X-Pro1.
The Fuji X-Pro1 was set for high frame rate mode, and popped off a full 23 frames in RAW + Fine mode, plus a latent 24th frame also, after I lifted my finger. Each image was about ~33 MB of data for the RAW + JPEG.
Times are how long the camera buffer took to clear (write all images to the card). The 400X card cut the buffer-clear time in half.
Lexar Pro 64GB 400X SDXC: 26 seconds
Lexar Pro 32GB 133X SDHC: 50 seconds
I’ll be sticking to the 400X or 600X cards now that I’ve seen these results, and I’m curious to test in the Nikon D800E once mine arrives.
Get Compact Flash and SDHC / SDXC cards on the Other Gear page.