From the study: "In fact, the chaos of the bulletin board and the chat room can have a profoundly negative effect upon the overall quality of conversation, a new study concludes. But when the talk moves into a less freewheeling environment, the level of the debate seems to improve." ETP shares characteristics of both, and I don't know of any other similar situations, except for other weblogs communities (inasmuch as you can even draw a line).