As a matter of interest - do most of you record to cf or sd cards ?
I've used both with no problems always Sandisk extreme pro. Its just I feel more confident with CF.
Has anybody been had problems with SD cards on Canon 5d3 ??

I have used SD cards with 5DM3 on occasion and never had a problem... I usually use CF cards though. However, I do wish CF cards had a copy-protect feature like SD cards do!

I use both on a regular basis. I generally go into a long day with both slots loaded, and don't really think twice about which I'm using.

Same as Bill. Both slots loaded and both seems as good as each other. Sandisk Extreme Pro, 32GB no problems.

Yes I load both slots but recording has stopped occasionally when its recording to SD, It means you have got to watch that red light like a hawk, I am reading on photography forums about the CF slot being faster,

Don't Use SD Cards with Your Canon 5D Mark III If You Care About Speed (http://petapixel.com/2012/06/24/dont-use-sd-cards-with-your-canon-5d-mark-iii-if-you-care-about-speed/)

This sort of stuff makes me paranoid! I think I'll buy some Sandisk Extreme pro 64gb CFs just to be on the safe side.

I use CF and SD card all the time, never had a problem. I think if you got problem recording to SD, the problem is with that SD card (maybe not formated in a long time). It is cameras out there with higher data transfer that record to SD without problem.

Yes I load both slots but recording has stopped occasionally when its recording to SD, It means you have got to watch that red light like a hawk, I am reading on photography forums about the CF slot being faster,

Don't Use SD Cards with Your Canon 5D Mark III If You Care About Speed (http://petapixel.com/2012/06/24/dont-use-sd-cards-with-your-canon-5d-mark-iii-if-you-care-about-speed/)

This sort of stuff makes me paranoid! I think I'll buy some Sandisk Extreme pro 64gb CFs just to be on the safe side.That's irrelevant unless shooting stills in burst mode. Even the slowest SD card on the market today is fast enough for recording video. Faster cards are better for offloading the files to computer.

Maybe I missed something here - has anyone had any issues similar to above - this is worrying,

That's irrelevant unless shooting stills in burst mode. Even the slowest SD card on the market today is fast enough for recording video. Faster cards are better for offloading the files to computer.

The SD card speed also applies to shooting time lapse stills when there is a short interval between Raw still capture. I believe the CF cards are a bit more rugged and in this case faster. For just shooting video I have not noticed any issues in the SD cards.

Maybe I missed something here - has anyone had any issues similar to above - this is worrying,

I haven't experienced a freeze during video capture, but just the other day, I was doing a time lapse when about 20 frames into it, I got an error and the camera froze. I had never seen that before and and scared the hell out of me. After pulling the battery to reset, everything worked normally and completed the shot with no problems.

I was using the same 16GB Sandisk "Extreme" CF card I always use. It's rated at 60MB/s and has never even blinked before... I tend to think it was more a camera issue that the card since pulling the battery fixed it.
Pretty scary though...

There is a theory that the CF cards are actually less rugged than SD cards as those dozens of little pins are far more likely to get damaged than the flat & broad contacts of the SD card.

Objectively it must be easier to lose the teeny-weeny SD cards:-)

Objectively it must be easier to lose the teeny-weeny SD cards:-)

If you have a pet dog, then be careful. If the SD card falls then the dog can lick and swallow it. :)