This reflects my experience as well. The focus of my unit is absolutely spot on. I've been shooting a lot with the 100-400 II and the 1.4x II recently and even with this combo it is hard to fool the camera. Having the right AI servo setting can make a big difference. I do not doubt that there are a number of defective units floating around but I find it highly suspicious that with every new release when new bodies and AF systems get put into unfamiliar hands there is a spike in the claim of defective AF components.
Exactly. Without knowing the photo history of everyone who reports an issue, and how rigorous the testing environment, it's hard to conclusively say "everyone who reports a problem has a defective camera." I would put little credence in any sort of poll for that reason. If there was a huge number of returned units, the retailers would doubtless perk up their ears, even if Canon didn't say anything. For example, look at the light leak phenomenon in the 5D3; Canon acknowledged the issue and fixed any cameras which exhibited it for free. There was quite a ruckus about that at the time, yet only a handful of people on here seemed to be affected. I personally know no one who got a defective unit; only people who heard about it. My point is that it was severe enough to have gotten Canon to speak up publicly about it, yet it seemed to affect only a very narrow date code range. If Canon remains silent about the 7D2 - and I suspect they will - then I think we can safely assume that it affected very few cameras and was probably handled at the QC stage.