I'd say to keep adding to your DNG collection as is, because if you switch and you need to convert, 1-2% extra images won't hurt. RawTherapee is also a RAW imag

I'd say to keep adding to your DNG collection as is, because if you switch and you need to convert, 1-2% extra images won't hurt. RawTherapee is also a RAW image processing software that can help, instead of Darkroom, or maybe just to convert your DNGs to whatever other raw format Darkroom likes.