RAW or JPEG? Which one when?

To get the best results from the GH2 especially accurate colours and DR, I always shoot RAW through LR4.  With my G3 however I am happy to shoot JPEG for casual use as the later VENUS engine in the G3 and GX1 is much better than the GH2 one.

Also you can do much more effective PP from RAW e.g. LR4 gives great B&W conversion options from RAW files.

So to an extent it depends on the camera but also what you want to achieve.