CF as backup or SD as backup?

CF vs SD failure rate;
https://photography-on-the.net …showthread.php?​p=18165723

thanks for the info.

Come to think of it, i did have 1 sd card fail before. It wasnt because of the flash memory but instead that lock tab broke off and something inside locked the card up. Maybe I should just continue to stick with CFs as mains, nothing movable that can easily be toggled like that.

Lots of good info in the thread. One missing note is if you are shooting a 5D MK III the
SD interface card was not the latest and greatest when the body was released. The CF
interface in the 5D MK III is the faster of the two interfaces. May or may not influence what cards you shoot with.

110yd

I shoot RAW to CF as Primary and RAW to SD as my back up on my 5D Mark III's.
I upload from CF as well. Clunky fingers at times. Easier to grab etc.
I have a matching set of cards for each CF/SD combination. Sandisk Extreme 32 GB CF, SanDisk Extreme SD 32 GB. Also each pair is numbered so I know what cards match with each. Imagine all of your cards getting thrown together during a job, vacation etc.
Sure it's an expensive system.
If I am shooting sports in AIServo for example and want the longest burst, I remove the SD completely.
If am doing paid work I can leave all images on SD and store in safe keeping elsewhere.

With all that was said here, I ended up just sticking with CFs and leaving the SD slot blank for now.

I have used both options.

with the 1DX i had no choice, both slots were CF.
with the 1D4 i used SD, with the CF as backup - simply because i had an SD slot in the side of my macbook pro, and it was easier to use the SD card, instead of finding the cardreader in the bottom of my bag.
going back to the 1d2n and 1d3 - i used CF with the SD as a backup (a sandisk SD+ which folded in half to expose a USB connection - something i wish they made in higher capacities and USB3 interface)

I'm pondering the same, I have a wedding to shoot and I'm already noticing my current older SD card and CF card combo is really slowing me down during portrait shoots.

I've just ordered a 64gb SD card (90mbps) and a 32gb CF card (145mbps) and plan to shoot primarily RAW to the CF and Jpeg to the SD acting as the backup. Memory nowadays seems to fail very rarely so I don't see the need to have two copies of 40mb RAWs being written at the same time. I'd rather be able to capture more moments and miss less.