changemyview is an interesting experiment but I don't find the format lends itself to a completely impartial approach to the subjects discussed. In particular:

* It is one poster listening to and responding to many people challenging her. That creates an inherent imbalance to the conversation.

* Since the beliefs of one person are the meta subject matter, that person alone (not other posters) is implicitly pressured to change their view to seem rational and open minded. Everyone else does not have the same pressure.

* To that end, I haven't seen a CMV awarded in the reverse direction.

* The up voted subjects are subject to the general biases of Reddit.

/r/neutralpolitics might be of interest too.