The perimeter fencing is much cheaper and can be easier to maintain on larger areas. It also do not contain chicken's well although if chicken encourages to stay within core away from perimeter then you have a more economical option. Most of my paddocks defined by poultry netting have been inside the perimeter fencing where the poultry netting is used mostly to confine birds (juveniles) not inclined to fly. The netting stops smaller ground predators like raccoons, oppossums and foxes from getting at ground roosting juveniles. Those predators are harder to stop with perimeter fencing unless you have dogs that patrol frequently. Even with frequent patrols you will have troubles with Great-horned Owls at night and if dogs used to prevent owl-damage the dogs need to be able to get to where owl is when it comes in.
