If you need a lens with IS buy the 24 - 105mm !It's not f2.8! Jeez. What's wrong with wanting an 2.8 IS Zoom for the 5D2 that's equivalent to the 17-55 for the crop? Seriously, this is not a trivial matter. Some of us want to hand hold in lowish light.
A 1DX with a 24-105 will take care of all low light situations
I wish people would get out of complaining about lack of IS and think how they can manage without.