I agree with this view of the role of campaign attacks.

The main impact of campaign attacks, I think, is not to actually change anyone's mind but rather to familiarize everyone with the talking points of the side they agree with. In 2000, voters who valued "experience" turned out to favor Al Gore strongly. In the 2008 campaign, I think it's clear that voters who value "experience" will favor John McCain. That's not, however, because there's some coherent bloc of "experience" voters who shifted loyalties -- it's because "experience" was a Democratic talking point in 2000 and it's a Republican talking point in 2008 so people change which candidate attributes they value. In 2004, you could find a lot of Democrats who thought John Kerry military service proved important things about his fitness for office, whereas in 2008 Republicans are more likely to say that about John McCain.

We often hear that people wanting change or experience is a strong "driver of the vote," i.e. it causes people to vote for one candidate or the other. In actuality, it's equally likely that people who are already predisposed toward a candidate then grab onto a rationalization for their decision.