Which is more versatile a 3" or 2" backing plate?

[bcgreen]

I have been contemplating purchasing a small backing plate, mating to a drill, to get those small spaces.
I see there is the BOSS™ 2" Backing plate and the 3 Inch Dual Action Flexible Backing Plate.
Will the 3" DA work with the drill adapter and if not then my question is mute.