Red, I think it's mainly a case of the natives being better adapted to the Australian conditions (seasons of drought etc) The trout definately perform better if they can have access to either fresh cold water from either the depths of a lake or from the bottom end of a dam.
YakAtak, when comapring a trout and yella of the same weight I would say that trout are zippier and dart around more. They also put on a great arial show. Something I really enjoy in the kayak up close! However, the yellas initial hit can sometimes be much bigger, as they like the cod are an ambush predator that slam passer bys hard and then u-turn to their snag. Both can be great sportsfish.
JD, I've only fished in salt in Port Phillip Bay, Vic. I do this in my little Perception minnow with confidence that there's no big threatening sharks lurking there. I hope... Mick