I definitely don't hate NS, but observe that the vast majority of posters 1). are under 18 years of age, and tend to show their lack of maturity in their comments and posts, and 2). the vast majority of users actually don't even own a car - yet are happy to shell out advice and opinions as though they are gospel.
SAU users used to tend to be exclusively older, as the price of the cheapest import Skyline was $30k+. However, these days I feel a large part of the deterioration of SAU is the fact that a turbo Skyline can be had for well under $10k, and this opens the forum up to a myriad of younger users, who tend to type before they think on occassion.
Another big factor is the clampdown by SAPOL on imports scaring people away from the scene, or more significantly forcing users to be much more private in their discussions of mods/cars/cruises, which makes it seem as if less goes on around here.
Just my observations.