The AF issue is a "sh!t happens" thing, it could happen, I can accept that. But everybody here would be pretty upset to have it happen to a 6k lens within the first year.
...as opposed to a nearly $7K camera within the first year? Honestly, the 1D X issue is worse, IMO, because it affects pretty much all users who bought the camera before the recall, whereas I haven't seen a big outcry or recall of the 200/2 for 'gravel in the focus ring' - seems you were unlucky and got a lemon. Still sucks, though. I suspect it'll end up not being gravel (wouldn't you or the person you bought it from know that it had been dragged through gravel?), or the sealing, but something internal that's broken.
I can agree that the 1dx issue is worse because it affects much more people. But I had mine in for service but it never malfunctioned for me, and it seems to me that majority of serviced 1dx's wasn't having the symptoms, just the serialnumber.
I certainly hope something internal is broken, but considering the ring haven't been used and worked fine three weeks ago, I doubt it. But I can't know that until they open it. I also can't really know where the dust I see inside the lens is located. All I know are the symptoms not the solution. Point being when it has seen almost no use, it shouldn't have to be repaired. A D.O.A-lens would have been much easier to accept...