I am not trolling and hope this message is taken as constructive feedback. Regarding the bond @ 4% idea, consider this:
At the current difficulty (1.25m) and exchange ($6.25/BTC), a $300 5970 (hashrate 800Mhash/s) would generate $4 per day, or $122 per month.
Obviously a 5970 cannot exist in a vacuum. It needs a PC, electricity, cooling, space to run it in ... let's be generous and say all that infrastructure and support doubles the price of that card to $600.
So back to our calculations: a $600 investment would be generating $122/month. Or, putting it another way, a 20% return PER MONTH. You are suggesting the bond offer 4%.
I understand that if anyone doesn't like the offered terms, they need not accept. But, to me at least, a 4% return does not seem very attractive/fair when I am aware that you are making at least 20%/month from my investment.
What about depreciation of the $600 worth of infrastructure? What about difficulty changes?
I'm not sure you understand the difference in the risk profiles between debt and equity. If it were an equity investment, I'd probably want a bigger cut, but debt is higher up the food change. Even if difficulty increases, giga would still be obliged to pay out the 4% per month. Because he would be taking the higher risk, he needs to have the prospect of higher return.