Dear Platypus,
Thank you for your step by step description/images for the conversion of color negatives. I tried it out and it works quite well. I agree that the majority of the work can be done by adjusting the inverted tone curves. I also needed to up the vibrancy in many of the images. Interestingly, trying to adjust the saturation slider led to massive changes in color balance. I set up new presets for B&W and color negative conversions with inverted RGB and individual tone curves, respectively. At least it served as a start. I also agree that this should stay in DPL.
Thanks,
jim