At any sporting or action event, I'll have the Nikon D4 with me which I have now owned for almost a year and that seems a good point to reflect on ownership. Here then are a few thoughts on the D4 and why having a 16MP sensor is as much as you need at these events.
i) wide open for max light and subject isolation - here I was wide open at f/2.8 all day
ii) with a fast shutter speed, and I started the day here at 1/1650th second.
With these two variables fixed by the requirements of the environment, all you have left to play with to get the right exposure is ISO and in the morning with rain clouds overhead, despite being outdoors, I was at ISO 800. And this is where the Nikon D4 is a joy. Below is a 100% crop of one of those pictures that has enjoyed my usual 'low noise' preset in Lightroom, that is, it includes shadow recovery and sharpening but not noise reduction. Despite that, the image exhibits minimal noise characteristics and nothing more needs to be done with it, it's already excellent. On a Nikon D800, at ISO 800, noise would be visibly present.
I love the D800 for its ludicrous pixel count and the sharp images it can offer, but a sports camera it is not. Nikon have clearly decided that 16MP is a sort of optimal balance between competing factors and I wouldn't disagree. And of course, lower MP equals lower file size so bigger buffer and quicker transfer.
Rarely is surely the answer unless you want to heavily crop your pictures before publication. And even then, the D4 still fares well.
In my view, image quality can't be faulted on the D4 which is of course an uncontroversial statement for Nikon's previous flagship camera and one which, when new, cost thousands of pounds. But the point is, I never come back from a day shooting with the D4 and complain that I've been let down by an insufficient pixel count. In fact, every time I use the D4, I find I love it a little bit more.