with regards to optus cable See if somone else will contract you on to said cable ? the state of optus cable is a sight for sore eyes compared to telstras HFC with that said you almost never get 24mbps on ADSL2 so if the cable performs up to Spec then i would say Yes yes it will and go for it , i would argue for them to include 100mbps for free other wise just pay the $20 extra hopfully it will be of use if its not demand a Refund
I'll be happy if the 30mbps cable even gives me close to a steady 20mbps. The adsl2 barely touches 11mbps. NBN isn't coming to this place until early 2018.
The upload speed is the most concerning. 2mbps even on cable..