I have been using mk4 for good month and half by now. In this time I have been shooting about 20 alpine skiing World cup races, where skiers are A LOT faster then some speed skater. Next to that, you have pretty good chance, that you are standing somewhere on the hill, where you see skier just a split second before you need to take photo, so there's not much time to track them (opposite of speed skating, where you have huge amount of time, to track skater before you press shutter).
I was everything but happy with mk3. It was crap and shouldn't even be called camera. With mk4 on the other side, I'm quite happy. Sure there are out of focus photos. But they were also with mk1 and mk2. In general I would say there's less out of focus photos with mk4 then it was with mk2, and for most of them, it's operators error, not camera error (with mk3 it was camera error, and percentage of in focus photos was pretty much equal as percentage of out of focus shots with mk2 or mk4 is).
So to be honest, I don't care what Galbraith say this time. If it's working fine for me, I'm happy with it. And to be honest, I do get feeling from time to time, that there are some thing which we don't know behind all this. Is he all of a sudden just Nikon fanboy? I really doubt, but it wouldn't be so impossible. Is there some grunge between him and Canon? Maybe, and it's much more possible then him being fanboy. Does he get a lot more money from Nikon then from Canon, and this influence part of his results? Most likely. But I'm pretty sure, noone of us will never know real answers to these question. But personally I take his reports with a bit of safety margin.