Long Term POR-15 users - Are yo still happy with the product?

locally guys like to mix it with rustoleum , por 15 goes hard and prittle
like porcelin and the mix makes it less prone to shattering when I redid my trunk I found that even tho it appeared to be good once you cut the metal out it was bad inside the por 15 , I went with 2 part epoxy prime on all the new work .