[d_j_b]

Google's model rests on the assumption that all the ads on the site will be Google ads, and as such this scheme comes with a fairly heavy incentive for content providers to carry Google ads only.

Declaration of interest: we're trying to do something in the same space with content-that-should-be-or-is-paywalled with Financial Times articles on The Browser (http://thebrowser.com)

[koala_man]

If the model is that you bid on your own ad views at market value, why would it incentivize content providers to carry Google ads only?

[daxelrod]

People will likely complain that they paid for Contributor but still see ads on your participating site.