I do completely agree with TheAnalogKid:
Rentals are just another way to make normalized income, a steady stream which may be lower, but suffers from less variance.
Whenever i want to rent some hash, I'm sure the the hashes aren't going anywhere but to our pointed pool, as a renter I will constantly check the hashrate i rented....as long as the hashes speed is running accordingly, that's it, no problem at all.
Cheers.