In this paper we present an ongoing experimental study on the potential of e-participation devices for local planning processes. The tested tools are semi-structured annotation devices. Our goal is to evaluate the effect of these tools on the quality and impact of local planning debates. To test these potential benefits, we invite young students to debate role-playing-games. After field visits and encounters, the students are randomly assigned into two groups in which they play the role of 6 types of stakeholders. Following Computer-mediated Communication and deliberative theories we expect that the tested e-tools enhance interactivity, equality and argumentativeness of the debates (quality) and then argument repertoire and opinion change (impact), without important flaming differences. In the first two experiments, most of our hypotheses were confirmed. Other experiments will occur by the end of 2009 to test the reliability of these results and explore the impact of a more usable annotation tool.