Given that you are flying in premium cabins anyway , I would think that it would be of limited benefit. You already have some travel planned; when you do that you will be able to meet the requirements just based on travel done

I would also suggest looking at whether the Qantas scheme is likely to be the best to credit to given your description. e.g. after july 1, crediting BA to Qantas will likely not be as good as currently is; perhaps worth looking at crediting to another scheme such as AA where may be able to get better value from the miles earned

If your membership is nearly up for the year and need to do 2 sectors, you need to figure whether a cpl of hundred dollars is worth it to attain status. SYD-CBR-SYD is a fairly quick trip if you are based in Sydney