IGN staff are really one of the last ones who should call some other popular gaming related things bull, they are among the worst, unreliable, biased, bought sources of gaming journalism ever.
VG chartz is always quite near the reality and they constantly update their estimations when official numbers appear. VG chartz is the best source for console sales figures available, there is simply nothing else similar, this is the reason why VG is still popular.
I disagree with the bold... VGC most times is far way from the reality but I agree with yout others points
Adjustments less than 100k after the trackers numbers is fine but we see more ~600k, ~400k, etc adjustments here that makes the numbers not even close to the reality.