Yeah, that whole rrod argument is getting old. These numbers are always skewed since alot of people buy multiple consoles (both 360 and ps3). I myself bought two, but sold one used.
I do agree though that X1 won't reach the heights of its predecessor. Then again, I don't even think PS4 will reach those levels since I believe this generation will drop off much earlier.
What I do wonder though, is how much ahead of the 360 is X1 in the US right now, for the comparable time period?