I have been switching back and forth. At a wedding I would shoot RAW on the Compact Flash card and Large Fine JPEG on the SDXC card. Otherwise, I shoot Large Fine JPEG on the SD card and overflow on the CF card.
Did you order the 64GB SanDisk 95MBs SDXC card? For some reason mine is a lot faster (Read & Write) than my 32GB Lexar 600x UDMA CF card. They are about the same price.