I'm inclined to think a PoC (or whatever you want to call it) would be useful for some things: - a tangible and cheap way of showing the customer how you think

I'm inclined to think a PoC (or whatever you want to call it) would be useful for some things: - a tangible and cheap way of showing the customer how you think you can solve their problem - getting concrete feedback on that solution (you're both talking about the in same, tangible thing) - using it as a foundation for the "big" project. Not its code, but the ideas behind its UX, flow, treatment of data, whatever is the main crux of the solution can be made tangible in a PoC and be used as a reference for the next step, ie making a production-worthy application - the PoC can also show that what the customer wants is in fact a bad idea.