I don't think they ever really took off in Oz. Expensive to get over here and not that brilliant really. And of course in those days real racers didn't ride thumpers. ADB saw to that!
I only recall ever seeing one raced - it featured in a few races in SE Qld but I think the rider was a C-Grader and it never did especially well.
Maybe if they'd offered it at a reasonable price and registerable it might have taken off. You only have to look at the success of the early XR500 Hondas - once they got ADR they really took off.
I suspect there were no more than 6 in the country in the late 70s. Hannington's, Addison's, the Stayt bike, the one I mentioned in Qld, one that was for sale at CD2 and in VMX a few years back, and possibly another in Victoria. Like Maico 490s, there are far more of them around now than back then!!
I was just looking at Rob's piccy of the ex-Hannington bike that I owned for a while. It sure looks nice now, and it's really neat that its entire history is known and it's still in the vintage clan doing what it was made to do, 30 years later!