Thanks for the response. Last time I tried ansel this option wasn’t available.
It looks very good on the smooth images showcased, but real world images present a tougher problem. For the below example, I have tried to use the same modules at the same settings in both ansel and dt (though slight differences may occur), using filmic v7 so they are comparable.
Ansel with harmonic transposition:
darktable with inpaint opposed:
darktable with segmentation:
darktable with segmentation trying to smooth transitions:
Ansel with harmonic transposition combined with filmic reconstruction:
darktable with inpaint opposed, combined with filmic reconstruction:
Harmonic transposition does appear to do a nicer job with the clouds - which matches what we would expect to see based on your given examples, where the images are smooth and colourful. But it also gives ugly magenta and green colours around the branches, making it unusable for this image.
Inpaint opposed and segmentation aren’t as effective with the colours or smooth transitions, but don’t have the ugly green or magenta, doing a finer job of the texture.
So it seems to me a case of different algorithms for different use cases, and would be good for a program to ship all of them. But it is exciting to see what harmonic transposition is capable of. 
Others may be able to obtain better results than me, the image is here: