I’d be interested in your thoughts on that cfast card David, I didn’t have much luck..? I now use the delkin cfast paired with Sandisk Extreme Pro’s
Well I set the camera to record to both cards keeping the CF as the playback card and everything worked a treat, checked both sets of shots and all good so for me it does exactly what I need with a backup as I go and for £24 instead of a couple hundred.
One thing I did find which I can't see how to change - if I go through the images on the camera and delete a couple it only removes them from card one meaning if I was to shoot 1050 and delete 50 on the CF I would have the 1000 but the cfast would still have them all. Great if you accidently delete one I guess but not very good as a direct 'copy' if you know what I mean.