I don't know much about the ZP5, but I do know from many sources that the NF optics are pretty darn solid.
I even recall one of my buddies who spent a fair amount of time working on sniper teams over seas saying, "We always new we could trust our Nightforces. The Leupolds and even the Schmidt and Benders sat on the shelves in the rear."
I've spoken to a lot of people with first hand experience "working" with NF optics, and every time they seem to carry that durable prestige.