I'd support debates in these multiple formats. Having debates on Youtube, for instance, is exactly the kind of change that we need to import activity. Message boards are old hat, they're a thing of the past now. New mediums like through Youtube or perhaps audio-only through Soundcloud would be perfect, and add more realism to this whole thing. One debate in IRC would be interesting too, just to see how well it plays out. Everything should be tested first before debate season, imo.
Just think about what's done IRL. TV Debate=YouTube. Radio Debate=Soundcloud. Print Debate=Forum. Internet Debate=IRC. There's all those different formats IRL, so it seems logical to apply them here.