And I think the solid relationships with big publishers is the big part that's hard to replicate.
That said, you could probably more easily approach smaller (more local?) publishers that are more willing to experiment to get traction. Is that what you're planning on doing?
Would also say, there are tons of blogs out there with dedicated readerships in niche, but high value demographics (to advertisers). This is perfect for them.
While we hope to work with big publishers too, niche blogs are an awesome place to start. As you say, they provide a self aggregated group of individuals with a common interest. They're perfect for polling.
That said, you could probably more easily approach smaller (more local?) publishers that are more willing to experiment to get traction. Is that what you're planning on doing?