It's very hard, if not impossible, to point a finger and say how much (or little) a 2 day sales period will effect Gears 2, as opposed to other major X360 games.
If you look at X360 games, there's a pretty simple trend for top-selling releases:
From BKK:
02 Grand Theft Auto IV 360 (514k) --- 5 Days of Sales
04 Halo 3 360 (411k) --- 4 Days of Sales
08 Gears of War 2 360 (~247k) --- 2 Days of Sales
13 FIFA 09 360 (201k) --- 2 Days of Sales
Now, it wouldn't justify everything, but with an extra 2 days of sales, we don't know how many units would be sold. Its new territory to analyze 2 days of sales, so please forgive me for any inaccuracies. The last thing I want to do, as a VGC-er is overbloat sales when they just aren't there. Time will tell how well Gears did in comparison to Halo 3. But I think that by this time next week, we'll know how close, or how far, we were away from the truth.
Back from the dead, I'm afraid.
