Actually it's used to correct all light falloff/color cast. So in your case, it would be no different than say, using a 28HR, or 32HR-W, with no CF on center with no movements. Thus there will be some light falloff around the edges. The LCC will correct for this very well, so I believe in your situation, the same should work also.
The only difference, you have a 120mm macro, and C1 should have a correction for that built in. But I agree, it's sure worth a quick try.
Just make sure to keep the aperture constant, and if necessary change the shutter speed to allow more light in.
Paul C