I’ve had problems with processing .RW2 files taken with the Panasonic S1, S1H and S5 in RawTherapee (5.8) since there occurred a lot of clipping in the images. I first thought that this had been a problem of the cameras tending to overexpose in automatic metering. But it turns out that this is due to RT clipping values of the raw camera files.
When I use Adobe DNG Converter to turn the .RW2 files into DNGs, (significantly) less clipping occurs. On top of that, the raw histogram of the images differs: