I think I'd depend on the developer's ability. Like, a professional game developer (mostly non-indie guys) doesn't post demo like we developers do here for some reasons (one would be not finishing demo by talking instead of working), while developers like us post it to receive feedback and w/e, so I think I'd be better to make a demo and receive feedback, but that would be up to you. I'm glad if someone corrects me in anything, hehe 