It's commonly said that Brandywine is very susceptible to disease. However, in my personal observation, Brandywine Pink is one of the most resistant to the pathogens that cause damping off for me, this year. The only variety more resistant that I'm growing is, I believe, Brandy Boy F11.

What are your observations with it, regarding disease susceptibility/resistance? (And which diseases?)

I'm not sure which damping off pathogen my plants have been fighting this year, but it manifests more often when it's cold.

I’ve only grown Black Brandywine (PL) so can’t give feedback, sorry!

Having grown Brandywine in several of its forms disease susceptibility is not a problem. The better my cultural habits, especially the mulching program the fewer the disease problems. No more diseases than any other variety. For me, disease is not a real issue and disease resistance only makes a few of days difference anyway.

I find that in my garden the PL varieties seem to be less susceptible to disease. I don't know if that is true for other folks though.