Shading comp. in WB section of EP3
If you shoot RAW as Klarno said, having it turned on will not make a difference.
If you shoot both RAW and jpeg, having it turned on will help the jpeg -- maybe.
If you shoot only jpeg, you will have to make the decision whether or not you want the camera to "fix" the falloff or do your own editing later. I keep it off always because any processing of a jpeg image is likely to have collateral affects.
I rarely use the jpegs but edit the RAW files. Not really sure why I include jpegs at all .... hmmm.