Paying for the privilege to speak could deter less qualified speakers from leading the discussions, though. It would keep the quality of conversation high I think. Thoughts?
If you're really interested in hearing someone, why not reduce the barriers to having them come speak? And if you're not interested, why let them speak at all?
It's bad form to ask speakers to donate their research, time, and breath, and then also ask them to pay for the privilege.
When I spoke at the CCC, this miffed me a bit.