There are lots of threads about the differences between CF and SD cards, but in a nutshell.
CF cards can have the fastest speeds, and are more robust. Someone may pop along and say what the fastest cards the 1DIV can take advantage of. Obviously if you aren't taking advantage of the 1DIVs burst speed, then card speed is not an issue.
CF cards can be more expensive than SD cards. There is a chance of damaging the pins in the camera, though that is very rare as far as I'm aware.
SD cards are usually cheaper, because they are used in more devices. They are also small, which some people prefer.
SD cards can be fragile, and because of the size and light weight, easier to lose.
Both types of cards have speed ratings on them.
I have an CF and SD card slots in my D300S, and I went for the a Sandisk Extreme CF cards which are rated at 60Mb/s, and also Sandisk Extreme SD cards which are rated at 30Mb/s. I use the SD slot as an overflow, but the CF card is the primary slot I use. I would have preferred my camera to have two CF slots as I think that is a better format.