What is better in CTR terms, an adsense that you see clearly that ads or an adsense that is "hidden" in the content. I think that the first solution is better for blogs and serious sites that look for good reputation and the second is better for people that don't know much about computers... Maybe the second can be more profitable, but will be people coming back and will the site go at long term?
I choose the second one. People who are not "net savvy" tend to click on ads.. that's my experience.. and I love to target them as my market