If you are planning to do this soon, be aware that flights through SCL will be unreliable at best (due to earthquake damage at SCL). Also note that the Circle Pacific fares book into L class (IIRC). This is very restricted and availability may be hard to get in popular times. The individual sector fares (quoted for a more competitive fare) may be in an even more restricted class making getting seats when you want them even harder (the SCL-AKL sector is usually very popular).

The Circle Pacific fare allows changes whereas some sector fares may not (without penalty)