Paint Or Undercoat?

POR-15 is not remotely similar to rustoleum.
It's extremely tough and very effective when applied properly to the right surface. It's messy, process sensitive, and paint doesn't stick well to it. On a rusty surface that I don't want to replace, it's awesome. On a new surface, I'd use something else.
On a sidebar, I have painted over POR by spraying it with primer while it's still tacky. Did it on a car I didn't car too much about and it seemed to work...