Have to admit, that after having a fin biter, and a boy who was just constantly ill, my HMPK is super healthy. He had a little bit of an issue when I first got him, still have no idea what it was but 5 days in AQ salt fixed it.
In my very limited experience, they seem to be a tad bit more... sturdy? than the long finned breeds, and boy! can they get some speed! I think the biggest thing is their fins are shorter, which are less prone to damage and rot which compromises the immune system of the entire fish as they fight off fin rot or whatever happens to be ailing them