Wow, you're on the ball. :) We have a very convenient way of expressing value here. If the prototype has proven solid enough to support an active and growing

Wow, you're on the ball. :) We have a very convenient way of expressing value here. If the prototype has proven solid enough to support an active and growing user population, then it has value, because it's cleared the first hurdle of software design -- making something people want and can use. A few iterations on said prototype before bringing in a technical cofounder is also a big plus-point. Those iterations are where you find out whether or not your prototype will be flexible enough to turn into a real product.