Few years ago I saw some statistics for UK SMEs/Bs(and I think that is true for almost all countries) that showed that within 5 years most small companies wind up. If that is the case then this statement of yours that "If the value of your shares went to $0, you would owe $0." is a serious threat to your business model. If you are betting on few big ticket wins then that could be a very uphill task for you as you do not have any leverage over the companies; if you do then I would like to know how.

BTW, how will the interest and the share upside percentage be determined?