And again I wonder how smart I was (and you) to sell that lens. I probabaly have to think of getting the 300mm f2.8L IS II ...
Hi Eldar, yes, the f/2.8 is an absolute must, I would not have sold my 400 if I hadn't already owned the 300, goes with me everywhere, 300f/2.8L II + 200-400f/4 + 1Dx, match made in heaven.
To give some idea of what the Original scene was I've attached a grab of the Original RAW out of the Camera, converted to jpg, Not wanting to start a DR war, but even for Canon Sensor Knockers I think this goes some way to showing what the Canon Sensor in the 1Dx can do when it comes to retrieving detail.
The other thing I forgot to do in the Original was use my Strobes, unfortunately they were attached to my 200-400 at the time and I opted to go with the f/2.8, decisions decisions.