I am working on a set of experiments that may lead somewhere on the Rodinal trail. I made a solution of p-aminophenol base in glycerine such that 10 ml of it would contain the amount of p-aminophenol that is probably in 1+50 Rodinal working solution. Exactness is not critical at this stage. Adding enough KOH to make the pH over 12 makes it as black as a coal mine at midnight with the hatches down, but develops HP5+ in 16 minutes at 70 F, which is about what the Germans would put on their chart if they believed in CI < 0.65. Next, I made the same solution but added the 7.9 grams of K2SO3 that one would get in the working solution by adding 384 grams per liter of stock, again making pH over 12. 9 minutes now gets normal contrast. I don't know how much enlargement it would take to make a significant difference in grain or gradation. 30X hasn't done it for me.
Back to the dungeon.
I still need a comparison to something like D-76.