Plus Japan (25k+), would equal a bit more.
Microsoft endorses MyGamerCard, but doesn't actually give MGC the information on the cards. I am unsure how MGC has so many users outside of user-submitted tags (maybe they farm data from various leaderboards? that could explain it, as only gold or close to gold would be there).
Remember, MGC is real-time, whereas we have an entire week's lag on reporting info. Therefore, as of Saturday, I believe it'll hit it in 1 and week + 1 day or so (by next Sunday's entire posting).
This *should* give FM2 around 50k sales in the US, plus (most likely) a similar or even higher amount in Europe (the sales drops have been far better in the UK)
So, as of when I calculated the numbers:
US (380k) + 30k (6/7th of NAs next cume for Forza, approx.) = 420k
Europe should be no less than 50%, therefore another 420k
+ Japan's 25k (again, 6/7th of whatever this week's sales are, probably 1k)
That'd put it at, even a low number (since I do believe FM2 has probably outsold it's US counterpart) would equal, at minimum, 865k, which by using the 4.0*MGC Cards is within 20k, or 2.5% of my estimates. And again, if Europe was even 10% ahead, that'd be within my multiplier's range.
