I keep the raw.
My point in converting is because darktable (or any other free software) cannot read Nikon Z9 High efficiency raw formats. The Adobe converter can.
Altohugh highly unlikely, it may be that some time in the future I will be able to dispense with the Adobe converter. Therefore I keep the raw so that in such a circumstance I would be able to make use of darktable’s de-mosaicing alternatives, should I find it beneficial.