I think this is a really important thread and raises a lot of good questions.
So, my experience with launching products is that getting feedback (written or spoken) is always nice, but what actually determines whether or not a website or product will take off is user behavior.
People don't always know what they want until they see it. This is why I am averse to focus groups and surveys when deciding the best way to market a product or whether or not people would use it.
If you have not already, I would highly recommend reading the book The Lean Startup by Eric Ries -
http://www.amazon.com/The-Lean-Startup- ... 0307887898This idea makes me think of how when Tim Ferriss was deciding on the name of his book, The 4 Hour Work Week, rather than asking people which name they liked best from a variety of titles, he ran a bunch of google ads that just went to landing pages and measured click through rate and other stats. The "4 Hour Work Week" title performed best, so he went with that.
After having the failed conversion from actual 'hardcore' communities, I was able to compare and see that the people I had gotten feedback from pre-launch were more like what I was calling 'casual' (semi-engaged).
I've determined that the idea appeals more to semi-engaged style participants than engaged*. But I'm not sure how to identify a semi-engaged person. I'm not sure how to promote to them since they don't really aggregate anywhere.
Cool. Awesome to see that you are conducting market tests. So, in my experience, it's near impossibly to target one very specific group of people initially (unless you are paying for specific ads). Creating a funnel that delivers you the type of users you want takes time.
I would start off engaging the creative types on the whole and then over time, you'll learn the best ways to target the type of creative person that is ideal for your website. In addition, you'll being to tailor your website's copywriting for that person so that they convert into users at a higher rate.
It takes time to target your ideal users effectively, but I do think there is value in engaging the larger community. For example, in a previous recruitment software startup I did, people in the community would point customers our way because we made a good impression and they knew who we were, even though they didn't use our software themselves.
Now, my preferred method of getting in touch with target users online is inbound marketing. See:
http://www.hubspot.com/inbound-marketingIn-person, networking and following up is best.