I shot these last Saturday handheld on my 1D X, exclusively with the 70-200mm f/4L IS.
A couple comments from my experiences with the 1D X this weekend:
First, the higher frames per second helped a lot. If I timed everything in the ballpark of when the troops were going to fire, and I just held down my shutter button, I couldn't miss it. Yeah, it goes by the generally negatively-viewed method of "spray and pray", but you know what? Sometimes you need it. The 12 fps didn't disappoint at all. Additionally, the buffer was large enough to take a lot of consecutive RAW shots and store them on my memory card without any buffering delays.
Second, I was pretty under-exposed in some shots, but I was able to bring out the shadows in their clothing, for example, with ease. The RAW files allow me quite a bit of latitude during post-processing to overcome my mistakes while shooting. Overall, I was pleasantly surprised that the metering was quite good, especially in situations where I needed speed and accuracy, and exposure was an afterthought.
Third, the sharpness was very good considering I shot many of these photos handheld at 200mm, and some are shown at a 100% crop!
Fourth, it was raining most of the day. I was there for several hours shooting in the rain, without an umbrella or a plastic bag around the camera. I had a hood protecting the lens, but that was it. The 1D X performed very well through the inclement weather, and I wasn't worried at all about the wetness.
Anyways, thanks for looking, and I hope you enjoyed these photos!