You get a lot of the mud basher and rock climber setups down south but out here you end up with something of a compromise that can sorta do it all (carefully).
Most of all you want to be able to ride the tops of those corrugations at about 80kph. Any less and you shake the 5hit out of the vehicle, and any more and you need a lot of talent if anything goes pear shaped. The terrain off the roads/tracks is very unforgiving and will encourage you to go turtle (over and over again).
Having said that, +100kph is not uncommon on the marbles if the conditions are right. The problem is the conditions change rapidly without warning (bulldust and washouts). Concentration is a must, and as soon as I go dirt the centre diff gets locked so that front and back are spinning at the same rate.
A good suspension setup like what I'm doing when it's new will make you think you can go faster/harder safely. I'll have to keep reminding myself to back off before I break something.