Well I'm interested. However, I'm concerned about both parties being legally bound to the terms you have outlined above.

Without a contract you could split, and never be heard from again, without ramifications, and please note this is just business, I'm not implying anything about you. I'm only speaking from a business standpoint.

For example, someone could do a design for you, and without a contract, or the ability to monitor incoming revenue, you easily have the upper hand. You could claim that the business earned $10 this month, when it really earned $10k (example), thus the giving the designer $0.70 instead of $700. Additionally, you guaranteed at least $5000 in your above statement. Without a contract, you actually owe nothing.

My concern is business, and actually getting what you promise out of the deal.