No experience here, but keep in mind the dick acts and feels like a muscle, but it is not muscle tissue. Would pip be worse, less, the same? Eventual scar tissue would be a bummer if you begin relying on this and have increasing trouble injecting. We compare normal IM sites as to nerves and blood vessels, pretty sure dicks have lots of those. Porn actors are gtg anyway, maybe only doing this when filming requires MANY hard-ons within a short period of time, more than we expect of ourselves? Sounds like last-resort stuff to me.
Taddy, you are brand new here. Also keep in mind this is a board where ppl normally ask about training, diet, and ped use. The OP for this thread is trentracks, he is very, very "different."