This is an awful deal; you know they'll never pay the amount that they owe. Why else would you be willing to sell at 10% of the earning potential?
One in hand is worth two in the bush?
I'm not prepared to put 6K on the line, but someone might be prepared to based on the potential 60K profit, don't know.
Look in the pyramining thread, they haven't payed out very much, if at all, recently.