As a 1DX user I agree with most of your statements below:
"From what I saw, the 1Dx files did not hold up as well as the D4s nor the sony sensors at higher ISo's for ISO and dark/shadow retention.........many 1Dx owners I know also reported the same and that is what I have seen on comparison images. I agree with some of your assessment. the current 1Dx is very usable at 10,000 ISO. I even feel 12500 is a darn good file. I still feel 25600 is No where in the ballpark to the Sony Sensor......not even remotely close......and it cant touch this D5 release"
The D4/D4s definitely have an advantage in high ISO noise performance - not huge but certainly demonstrable. None of us can really comment on the D5 as we haven't used it yet. Whilst there are some very encouraging "Test" images out there we will have to wait to see what reality brings - I am expecting the D5 to be very good indeed in this respect. Perhaps an example of what I am getting at is the results being obtained with the Canon 5DSr. From the initial reports and "Tests" I was expecting it to be wonderful at 800 and, maybe, 1600 ISO. However having recently seen (close-up) rather large prints taken at 6400 ISO I have had to revise my opinion of this camera! Far better at high ISO than the reports suggested. Of course it can (and usually does) go the other way as well so I think judgement on the D5 should be postponed for a while.
My main question is the AF performance of the D5 on Nikon lenses. Having directly compared the D4 series to my 1DX and Canon SuperTeles Nikon have a LOT of catching up to do here! All the extra AF points of the D5 are irrelevant if none of them can, at least equal, one of the AF points on the current 1DX. For my uses the Nikon D4 series (with Nikon SuperTeles) were a noticeable step down from Canon (note I don't have Mk2 SuperTeles) and a potentially better sensor is of no consolation if I am not getting fast/reliable enough focus in the first place. As I said, in a previous post, I hope Nikon have cracked the AF - Nikon shooters deserve it! Then if they revise/update a number of their lenses Canon may get worried. I hope Canon do get worried! It will be better for all of us!
Life is for living, cameras are to capture it (one day I will learn how!).