Wandered along to a bucking bulls night at the local hotel with a friend of mine and shot some of those. Did some track cycling work, nothing too demanding, and no team sports. Not great results at either event. Could have been the light though as both were in dark venues.
I just found the whole process of selecting a focus point and sensitivity etc to be a bit more taxing on the grey matter in general. Obviously, that would be the same for the 1DX as well as it shares those functions with the 5d3. It just takes a bit of getting used to I've found. Little things like the AF points only lighting up red when on a dark background and being black the rest of the time. I'd like to be able to put that back the way it was with say the 1d3.
Don't get me wrong, I'm not saying the 5D3 is rubbish, because it's not. It did a creditable job, but my keeper rate did go down. I'm just struggling getting used to the changes. I still prefer to pick up a 1D and use that for sport.
Now having said all that, if you were considering buying new, then the 1D4 is more expensive than a new 1DX.
http://www.d-d-photographics.com.au/...y-Only%29.html
http://www.eglobaldigitalcameras.com...r-cameras.html
If you're considering buying secondhand, then the 1D4 would need to be very cheap indeed to make it worth buying over a new 5D3 (grey).