You can read about it here:
As I see it, it's all about 3D-performance.
But I recall that the upgrade is important if you wish to update any lens as well. That what they told me when I updated my Sigma 30
Olympus XZ-2 iHS
Panasonic Lumix DMC-GX7
Panasonic Lumix G Vario 45-150mm F4-5.6 ASPH Mega OIS
Panasonic Lumix G Vario 14-42mm F3.5-5.6 II ASPH Mega OIS