Question on lean startup approach

I am coming across a lot of material (blogs, books and videos) about lean startup. The overall approach is nothing new but the availability of a lot more details, case studies and statistics are making huge impact.

The iterative approach to validate the business assumptions makes perfect sense. However, I have not been able to find any recommendations for one particular point, and hence my question.

So the larger product/service vision at the concept/idea stage consists of several assumption, and as a founder you have list of features you think the target end state product should have, and the approach should be to create the list of features for MVP and implement that after confirming (and tweaking if necessary) your assumptions with a set of prospective users.

My question is - When you approach prospective customers for feedback (assumption validation), is it better to discuss the grand vision (which might have several value adds to their business), or just the assumptions related to MVP (first set of features)?

Those who believe in this approach and have done it - Do you take just the prototype to explain the solution? What else can be helpful to gather feedback?

Thanks in advance.

In my experience, there are really two parts to this process. One is the face-to-face interaction with customers, where you are trying to get a qualitative sense of what problems they face, what their motivation might be for engaging with your product, and how they find out about products like yours. This is the part of Steve Blank's customer development process called customer discovery. At this stage, you want to talk to customers about their problem first, and then only if you get confirmation that your hypothesis is mostly correct, should you proceed to talk about your solution.

Either way, this step is all exploratory. The goal is to have a clear hypothesis that you can then test. (For the science-inclined among us, I'll add that this should be a "falsifiable" hypothesis, too.)

You have several choices for confirming or refuting this hypothesis. You could do the second customer development step, "customer validation" and ask potential customers to pay you money to pre-order your first version. You could build a minimum viable product, and then measure the response of actual customers to it. You could start running split-test experiments, each of which tests a different aspect of the hypothesis, and compare the results. The details will have to vary depending on industry and the specifics of your product development capability.

The important thing, though, is to separate your customer exploration from your more empirical testing. Both are important, and establishing this rhythm early on helps a lot as the company develops: qualitative exploration for hypothesis generation, quantitative testing for hypothesis validation (or refutation).

Does that help?