Hi Sander:
I only split an recombine with different weights, I don't do curves or histogram in the splited RGB channels.
I'm writing a new script for Narrowband combination, because when I processed "The Rossetta" it was very difficult to me assigning channel weights to avoid greenish tone due to high HAlpha signal, and reach color tones I want.
So, if you reasign channel weights you can turn a color tone to another one, while the image is still linear, without the need of using curves or histogram.
Of course, you can use the same method with non linear data, althought it isn't the main intention.
I'am not sure if you use H channel in curves you can modify only blue tones, or if green and red tones are affected too.
I'll try to publish script in a few days. I'm applying to my rossetta and I'am very happy with the result, It's much better than my first attemp with trial and error combinations.
Best, Silvercup