The points break down for mains go:
Novice (NBL Rookie:
Intermediate (NBL Novice)
All do go for the same NAG plate but with the Experts getting more points (harder class) they usually get the plates. This gives the Intermediates and Novices something to move up for.
ROC and Redline cup plates are based on age and class, so Rookie, Novice and Experts all have their own #1 plate.
With the qualifying you will see that Opens are huge at the ABA evens. They have mixed opens for Novice, Intermediate and Girls and then Open for the Experts (mixed age).
I like because if I go out and do good in the first moto I know I am garaunteed to make it out of the motos. If I screw up in the first one I know I still have a chance in the second moto.
Plus with the way they do practice you get a good amount of track time.