So we have finished our debates in English class this year, and while they weren't an unqualified success, they were much improved over last year. Students' arguments were much better prepared and much better structured. They didn't quite work all the way through the structure; their closing arguments were more like summaries than rebuttals, but they paid enough attention to their opening statements to make their summaries. Their cross-examination questions were often actual questions, and not just statements. Their statements of position were consitently backed up with traceable research, and if their sources were sometimes less than reliable, at least they weren't articles from the Onion. I haven't read their reflection papers yet, but it seems like they have gotten more out of it than last year's class.
There are things that they didn't do, a clear indication that they didn't know they were supposed to do them. As often as not, they just read off of their source material, which means that I saw the same 4 speeches 6 times. I don't know that they ever understood why I had them research both sides of the argument, but they did give some indication of arguing from a place of sympathy.