[Addendum to the original post: The next post attempts to clarify the positions of several, apparently contrary blog posts, as well as some of the comments generated by this post.]
One of the things I do for my "Sherpa" companies is help them raise money. Recently, I've had the same discussion with several of them: whether to have 'informational' meetings with VC's as a prelude to later, full-on 'pitch' meetings. My advice to entrepreneurs and startups is that, on balance, 'informational' meetings have more risk than reward -- so don't do them.
First, regardless of the nominal reason for the meeting, VC's always assume that entrepreneurs are meeting with them to pitch. VC's have money; entrepreneurs want it. That's the fundamental nature of the relationship. When the meeting is premised on the notion that it's just 'informational', there is a risk that the entrepreneur is too casual, not well-prepared, lets down his guard and does not put his best foot forward. And, because they're wired this way, that is what the VC is likely to remember: a lousy pitch.
Second, as I've written elsewhere, although I've never heard of a VC "stealing" an idea from an entrepreneur, VC's do learn from every startup that pitches them. No surprise: VC's, even in their field of speciality, can't focus as much on any single startup idea as the entrepreneur(s). The risk here is that, the VC, now smarter thanks to the entrepreneur, "passes" on the entrepreneur's deal (even though he wasn't being pitched) for any one of a number of reasons, but then meets another startup team that he likes and that is doing something similar, or hires an entrepreneur-in-residence with a similar idea. Now, the VC has a 'prepared mind' and can be of more help with what could turn out to be a competitor.
Third, the first thing VC's do when they meet with other VC's is talk about interesting startups they've seen. If a startup has just met with a VC, even for an "informational" meeting, that VC is likely to mention it to colleagues and other VC's, although likely not with the qualifier that "it wasn't a real pitch". Several months later, when the startup is 'really' fundraising and they meet with the VC who heard about them several months ago, the startup may appear shopworn; that is, the VC may well think something's wrong with the startup -- he first heard about them several months ago and they "still haven't been able to raise money".
In my experience, entrepreneurs usually give two reasons for wanting to have "informational" meetings with VC's. They think it improves their chances of getting money when they ultimately pitch the VC for real (because the VC will, in some sense, be more up to speed and a more sympathetic listener, and/or will be impressed by the progress made since the non-pitch meeting), and the VC might get so excited by the non-pitch that he makes a pre-emptive offer (i.e., one that is so high, no other VC will beat it).
Neither reason is good.
While there is an old saw that "...when you ask a VC for money, you usually get advice; if you ask for advice, you're likely to get money...", I don't believe it. The best way for an entrepreneur to get a VC interested in his startup is to have a great idea and pitch it in a formal, polished and impressive way.
And, finally, no self-respecting VC will make a pre-emptive offer (even to get a deal early) if he thinks that he's got the inside track on a deal. The only way to get a pre-emptive offer from a VC is to have other VC's interested. No entrepreneur ever got a VC to substantially increase his initial offer merely by presenting more data (even great, persuasive data), showing why the startup should be valued higher.
Entrepreneurs -- if you want to get a VC to make a pre-emptive offer, get other VC's interested in your deal.