Unfortunately, the newer version of DAZ Studio and Poser's Post Manager take their Gc settings from the Video Card programs.  To test this, activate your VidCard program and slide your Gc setting from 1 to 2.2 and observe the results.  The monitor image will become increasingly brighter, not darker.  Repeat the Gc changes within each 3D app and you will get the same.  Basically, changing the Gc in this manner is not the same as other ways of correction.  I did come across an article offering a more technical explanation which I will need to find again.