The Oz Class G hybrid provides for a higher level of service than ICAO generic G (where there is no DTI mandated), so it may well be the case that it is preferred by users over the more restrictive E. I started a thread in the ATC section on this topic to see what it's like around the world, and it looks like there are many variations of G in use, but ours appears like a higher one than most if not all ? Maybe this could be a valid reason to maintain the current easy A085 E base everyone is familiar with ?