The OP has asked whether Etihad's Diamond First Class on it's 77W is worth the additional 15,000 AAdvantage miles (60K miles) over the Business Studio on the A380 (45K miles), and whether Eithad's current 77W services to Oz might later be upgraded to the A380.
In regards to the likelihood of Ethad's Melbourne services getting upgraded from the existing 77W, as I understand it the intention is to switch to the Dreamliner late this year/early next year but that the A380 will only be servicing SYD.
As to whether Etihad's 77W Diamond First Suite is a third better than it's A380 Business Studio, I'm inclined to say yes - mostly - for the following reasons:
* Due to the smaller Diamond First cabin, and higher cabin crew to passenger ratio (you tend to get lost in the crowd in Business on the A380), service is more responsive and personal;
* Toliet access in the Business Cabin on the A380 frequently requires good timing or waiting, whereas it's typically straight in on the 77W First cabin (apart from the peak time of just before approach for landing); and
* Slightly better food and beverage, nicer presentation.
That said, I found seat comfort a little better on the A380 Business Studio (the 77W Diamond First seats are a bit hard).
Ultimately though, whether you think a third more points are worth it to go from the A380 Business Studio to the 77W Diamond First Suite really depends on you and what you value most. Either way, hope you enjoy.