Thanks @afre, I’ve already spent quality time reviewing @Elle 's articles. I use her profiles to make internal profiles for rawproc, but I’m finding I probably need to extract the actual dcraw profiles instead. They all appear to be linear gamma, which doesn’t then reflect the application of gamma with -g. Still investigating, will write a more definitive (and correct) account later.
Edit: Just finished extracting dcraw icc profiles for selected colorspace/gamma combinations, and dcraw is indeed encoding the gamma used in processing. Also, the primaries are pretty close to @elle 's LargeRGB profiles, so apparently no images were harmed in the production of rawproc 0.5… Still need to understand the histogram differences, more to come.