I use Rodinal almost exclusively. But with HP5+ I did not like results. When I started to use HC-110 with HP5+ problem was solved. I have bottle of HC-110 only for HP5+, tonality and contrast are great.
I had the same problem with HP5+ and Rodinal. I switched to Ilford DDX (that I use for Rollei Retro 80S) and got much better results, certainly a lot less grain.