Sadly, all warnings were correct: the average age was around 50, lots of older big guys and a few younger Asian guys (looking for a guardian?), most people wearing a harness. There were maybe 2-4 other guys of our age (~30).
Finding the venue itself is a bit tricky: look for the "Civic Hotel", but make sure to wear something decent to start with, as you will have to walk across a bar to get to their hidden club in the basement. The venue itself is very small, with a dance floor in the middle and an elevated drinking area and booths all around it. Drinks were cheap at ~$8 for a mixer. The music was the best we've heard in Sydney so far - electronic house and techno.
As fun as the music was, the crowd and small venue didn't make it worth staying for longer. I suggest to avoid this venue, and better go to a usual night at Arq or Stonewall, unless you're looking for a daddy.