gx1 vs gf1 in real iso

I have an interesting observation.

1. dxomark rates the gf1 iso 1600 as 2316 actual iso
2. dxomark rates the gx1 iso 3200 as 2737 actual iso

In this image noise is very comparable and I would give the edge to the gf1.

Now look at the shutter speeds 1/800 for gx1 vs 1/640 for gf1. That's only 1/3 a stop difference with the same aperture. Also the gf1 is around +.33 ev brighter (I doubled checked in lightroom when I equalized for brightness and it was .33 brighter. This confirms that the gf1's actual 1600 iso is very very close to the gx1's 3200 actual iso.

Any more thoughts?

Here is a crop from gf1 at 1600 iso from dpr's raw convert

Here is a frame from gx1 at 3200 iso from dpr's raw convert