Not that, but adding ascorbate to Rodinal makes a considerable difference in grain without much difference in other aspects. You must use the ascorbate or the pH does too far down. Mix 1 teaspoon of ascorbic acid powder with 1/2 teaspoon of sodium bicarbonate in a couple of ounces of water and when the fizzing subsides, use it as part of the water to make a liter of 1+50 Rodinal working solution. Treat it about the same as 1+25 Rodinal. This combination is discussed in www.unblinkingeye.com.

I don't know for sure what is in Diafine, but I doubt it will be as copasthetic as the ascorbate.