I don't have huge experience with this species but have seen half a dozen or so up around Blackheath. Your photos appear to match all the described characteristics, and other photos on iNaturalist, pretty well, so I have confirmed. Must be close to it's southern limit at this location.
Not much - it's clearly in the multipunctata group, but it's none of the three that we get in ACT that I'm most familiar with. It's quite different to a Sigma Darner (which is also further north), and there are no other multipunctata-type species in the region. So even by elimination, we end up with obscura.