An irl friend offered to loan me a thousand steem at 10% apr. He's not going to be as active on the platform anymore and has offered the loan so that the SP doesn't go idle. It was very kind of him given the higher rates elsewhere and I was tempted to take him up on his offer but may not. Here's why:
Calculation
1,000 SP = 2c upvote = 1/20 Steem
1,000 SP at 10% APR would mean having to return 100 Steem at the end of a year or about 8 Steem a month
Let's assume 100 posts in a month. That would mean the incremental earnings of 100/20 = 5 steem
Conclusion
So it looks like a shortfall of 3 steem per month. Granted, this is a very simplified calculation and i've ignored the curation rewards. Still, i can't see a way of making this work without a lower APR. Time to negotiate or maybe i missed something :)