I used to be able to do “production-line” tweaking of highlights, shadows, etc, using GIMP, in a minute or less. Whilst it still takes me longer in dt, I prefer the experience to the extent that when I do want to do an ultra-quicky I’ve now lost the GIMP rhythm, so… I might as well stay with dt. And do.
I don’t really do portrait-style removal of spots and blemishes. If I need to, I’m guessing that GIMP might be easier. But hey, I haven’t even mastered the wavelet section of retouch, so I’d probably be better off putting time into that. It’s on the to-do list!
I use rating and colour-tagging in dt purely as a culling/workflow aid. There are usually enough colours for the main people in my pics, and rating is easy going through the pics in Lightable full-window.
There are possibilities, eg tagging musicians, that would have been great to use if I’d thought of it from the beginning. But I didn’t. And I’ll never, ever catch up. So if I loose ratings/tags in some data disaster, it won’t really affect anything except current work.
Nutshell: I might occasionally use GIMP but could probably live without it now. I don’t do the kind of work that needs GIMP.
And I’ve learned to love darktable’s user interface 