I'm not sure if it's because I'm "used" to Eliezer's styles, but while I can recognize the two posts use different styles, both seem equally "appealing to read" to me. That said, I *feel* more "informed" and "convinced" by the 2009 style. One thing that really struck out to me as a difference between the two was that the 2009 explored more deeply the school principal example. Before reading the 2009 essay, I "believed in" the claim "It doesn't matter who started it; the important thing is to end it". I don't think the 2006 essay would have convinced me that this claim was false, but the 2009 sure did.

Unfortunately, this probably has a lot more to do with difference content than in styles, so I guess this might not be the most useful datapoint to use in your comparison.