Personally I would never pay that much more for an upgradeable fare unless I could be upgraded immediately (i.e. upgradeable booking class was available at the time of booking). That is a risk to be taken, and unfortunately you lost the gamble.
I prefer to play their game. $656 RT LAX-SYD, less $300 bump voucher I had reducing the cost to $356. Then used 25K miles and $10 tax to get from central MN to LAX. I will earn 45K to 55K miles depending on which bonuses they post.
So for $366 I get a trip to SYD and 20K-30K net miles. It is a deal I couldn't pass up.