A colleague of mine at work signed up to Optus cable around 18 months ago. During peak hours he gets a maximum download speed of around 5Mbps as opposed to the maximum offered on the standard plan 30Mbps.
I finally bit the bullet in November last year and paid the $89 plus $99 a month to get Telstra cable with 1TB quota. It is the best decision I ever made, my ADSL2 service I’d put up with for 7 years was only getting 3.5Mbps, now I’m getting great speeds all the time. I wish I had moved to Telstra cable sooner. I’m in IT, so use my service for work as well as private use, but I’m glad I finally took the leap to Telstra cable.
NBN is supposed to be available over HFC cable in my area in July - December 2018.
My parents have had Optus cable for years and they’ve only had a few outages, they don’t complain about download speeds during peak time, but my mum works from home so she only use the Internet during working hours and they don’t stream Netflix or anything so they probably wouldn’t notice if it was slow.