I can also confirm that the 3,5k and 3,3k modes work really well on the 5D3. I get similar results as Bender@arsch, just 2-3 MB/s less since I only have the old 95 MB/s SD-card. And I did not have to overclock it. I also get continuous recording at 3200x1800/10bitLL/24fps (16:9) and more than 400 frames recorded at 12bitLL and 0.0 exposure without a single corrupt frame. Thank you so much, Bilal and Danne for this amazing work and for bringing the 5D3 that far. I still cannot believe that the 5D3 can do this.
The only thing that I am missing in this latest build is the slow choppy preview of the flv anamophic mode which is a full-sensor readout mode. I use it a lot at 15 fps and it really works very well for wide angle landscape videography since it allows slow camera panning and provides very smooth results at 1/30-th of a sec. shutter speed. Unfortunately, flv preview becomes skewed when recording is started and I don't how to fix it. So, I was wondering if the marvelous 5x real time preview could be combined with the slow flv preview during recording so that both could be toggled with the INFO button. Also, I was wondering if the frame rate could be raised by another 2-3 fps in that flv anamorphic mode. Right now, write speed is about 75 MB/s (green indicator) at 15 fps, so there seems to be a lot of overhead for higher fps available. The EOS-M does conveniently 16.688 fps in its flv anamorphic mode and is very stable at that frame rate, no corrupt frames either. In my experience, 17-18 fps frame rate seems to be a sweet spot for optical flow interpolation to 24 fps in Resolve.