Ha I just recently made a post about this as well (I can remove my link if need be just thought it was relevant. I think I'm making around 14% - 16% curating currently.
I'm around 80% efficient though.
Glad to see where coming to similar conclusions on % APR. Wish Steemleo had some tracking features so I could try and start optimizing my curation rewards on there as well.
86% efficiency!
Nice one :)