In many cases, an MVP shouldn't take a whole lot of time to build. If this is the case, you're better off getting the MVP out there, and getting feedback from that rather than the demo.

If, on the other hand, the demo is getting consistently negative (or "meh") feedback from prospective users, you may want to re-examine your value proposition.

Obviously, thinking about your customer acquisition and sales strategy is always a good thing, and if there are changes you can make to your product development to make those things easier, do it. Just remember what people say that they want isn't always what they really want-- which is why it's good to get the MVP out there.