I actually work as an engineer/designer for a small business based in Queensland who build ploughs, including non-inversion deep rippers (somewhat in competition with Yeoman). We have in the last ~8 months sold a heap of rippers into WA in partnership with a local manufacturer, targeting clay pan breakup, pH remediation, etc. with a lot of success. It's interesting the way deep tillage and other mechanical soil management ideas are experiencing something of a renaissance out west at the moment.