That’s a kind of lock-in effect, that you have to cope with, when switching from one software to another.
Did you export your edits? Maybe, you want to export 16bit tiff files. Then there is at least an archive and you have a basis to do further edits in your new software (of course it is not completely non-destructive anymore in those cases).
I switched from Bibble/After Shot Pro some years ago and I don’t mind that I cannot access my edits any more. I could start Bibble or ASP, but actually I don’t do that anyway.
[quote=“anaxonda, post:1, topic:3563, full:true”]
Currently I have a Lightroom catalog (~20000 photos) mostly in the form of DNG’s.
From what I understand, my only option for preserving any edits is to load XMP files into Darktable. I’ve tried this, however am not too impressed with what gets transferred over. [/quote]
To do better, than roughly approximating the LR edit, you need to know how the LR stuff works internally and you need to know about the semantic of the LR parameter. I think, even the conversion of edits from one open source tool to another (e.g. RawTherapee to darktable) would be a hard task. Converting from closed source tools is nearly impossible. Even if you were able to translate LR settings, it wouldn’t be complete. Features may be entirely missing and what about the input color profiles?
So, my advice would be to archive the edits by exporting them into some format that is suitable for further edits and I would start over in darktable. There is no need to edit all the old images again, since you already archived your LR edits. However, editing old pictures again can be fun, but then don’t just try to recreate the LR edits. Enjoy the new possibilities.
Nevertheless, I think it is possible to “translate” things/procedures you typically did in LR into something similar in darktable. For example, adjusting the clarity slider in LR is similar to using the local contrast and/or the equalizer module (with clarity preset) in darktable. This thing called “dynamic” may be covered by the color zones module. However, this is about adapting your manual editing process, not about automatically translating LR settings. Sometimes I watched videos about LR edits, which can be inspiring for darktable edits as well. You just need to know how to do something similar in darktable.
Please feel free to ask how certain LR operations may be translated into the darktable. I guess most people here don’t use LR or never really did (me included), so you may have to give examples or at least some rough explanations what these LR operations actually do.