A few months ago I reported back what Canon had told me officially at Photokina – that the 1D C had some very minor hardware changes over the 1D X (like a headphone socket) but that the camera was fundementally the same camera with a firmware update to enable 4K recording. The Canon product manager was technically knowledge and utterly adamant this was the case, there wasn’t a hint of doubt in his eyes when I had this discussion face to face on the basis of mutual trust.
Later Canon were keen to point out I had got it all wrong and that the 1D C had a different circuit board, etc. etc. and was well worth your extra $6,000.
So why are there traces of 1D C firmware in the 1D X?