On HN there is plenty of posts suggesting startuppers not to ask investors to sign NDAs... but what to do when the other thing happens, when is actually the investor who is asking you to sign a "mutual" NDA?

# background: - We've previously developed a prototype of a web technology which has attracted the attention of an investor

- In a meeting with the investor they have informed us of a market opportunity, a specific niche, where our product could be adapted

- Parts of the conversation had sensible information and they anticipated that we would have to sign an NDA, however, once they told us the information, there wasn't (almost) anything that isn't already public information. What they are putting on the table is a good intro to the specific niche: basically they have the client whom would buy our product

- we've analysed the market and the requirements and presented them with the final ideas of the project to develop, some where based on our technology, some where other business opportunities that the investor hadn't thought of and that we could build.

- now, once the presentation is done, they are asking to sign a "mutual" NDA (which "seems" mild enough), in order to keep talking about the rest of the project.

# My concerns: 1- there's many things about the investor that make it an undesirable partner (some parts are good, but most are bad)

2- Because the market opportunity is real, very very big, and largely untapped, we maybe still want to pursue it, and we still would like to honour the "introduction" to the opportunity done by the potential investor

3- We are afraid that this NDA could be wrongly leveraged in the future, if we end up pursuing and reaching this market.

Here's a pastebin of the generic mutual NDA http://pastebin.com/e2ZUU5qj

Any suggestions? I'm only afraid that this could be a liability for future developments of our product if it somehow overlaps the market opportunity they introduced us to. thanks