In Melbourne I never experienced sustained speeds of below 9Mbps on ADSL2+ in two locations, normally 11–12Mbps.

But if you want a fast, stable Internet connection, move out into a small country town with a 4G tower (doesn’t need to be NBN). There’s much less congestion. Look around for plans, as most are expensive; I use amaysim’s 50GB/$65/28 days which is about what ADSL2+ would be in the country. Living in Stawell (a few thousand people) I get 20–25/12Mbps with greater reliability than I ever got on ADSL2+. I shall be moving to Navarre soon (~100 people) and get 45/15Mbps there.