Good post. My own estimates put the APR up around 30-40% depending on the "skill" of the curator as well as the compounding effect where all earned SP is powered back up.

One thing that may impact this is the fact that the main @steem account started voting with a large amount of SP yesterday. I am not sure if this is a one off for testing or if this is the start of them voting with it.

Also this little tidbit may boost our returns just slightly, though the details are still unclear at this time:

https://steemit.com/hive-192037/@spidemen/trx-integration-with-steemit-wallet