I understand where you are coming from. My programming partner is going to have ideas and expand on the original idea. Their ideas will add value to the business as it develops. Additionally, my partner will do much of the "lifting" to give this idea life since I cannot program. It is reasonable to expect to receive compensation for the added value of the ideas and the coding effort.
This is the sort of collaborative partnership I wish to establish. If such a partnership develops and there is great progress, I am willing to progress to the point of equal partnership as you have suggested.
I believe that the more ownership one takes in an idea, the more invested they are in the idea/business's success. I believe in providing that type of ownership incentive based on the progress made on the development of the code and the ideas my partner brings to the table.