Remember to set the mouse sensitivity in XMB to slow, it helps abit in ADS. Where do you want smoother? At aiming? Do you find yourself engaging at long range? Then you might lower ADS.
The profiles are close to eachother but i feel that MAG gives me more precise movement, it feels that in BF3 profile the acceleration isn't canceled as good. This is purely subjective. As to how it is different when the settings are same, I don't really know exactly as Skrilla hasn' replied to my questions of how the profiles change from game to game. I imagine that the games have different movement and acceleration curves which the profile has to adapt to so to get smooth movement on the mouse.
You won't ever get as smooth a movement as in COD as it's 60fps and BF3 is only 30fps. Also the aiming lag is still there.
I play with the aimon mat. Maybe will try another if I hear good reviews for one.