The jury (or the moderator) will remain out for a while regarding the format chosen by The Economist to host their online debates. Have a look at the latest.
Participation (judging by previous ones) is on a par for such a qualified public, even if it’s difficult to find. Overall the interface is not exactly clear. But there is no denying the effort to streamline the matter, nor the quality of the proponents and their artillery.
Online debates do have a habit of becoming meaningless, or at least hard to follow, when several dozen people participate. On the other hand, this format seems to provide just a spectator’s seat on a co-written blog exchange, where two people spar and the rest comment the sparring. And then vote. Good? Bad? Probably much short of what it could be… but definitely interesting.