> Anyone speaking in a "proper" session
(...)
> Anyone speaking in two or more lightning sessions

In reality, a speaker can or cannot afford to travel to Amsterdam, no matter whether is to talk 5 minutes one time, two times, half an hour or two hours.

I think someone doing a lightning talk should be able to request sponsorship and get it, either because is a good speaker with an interesting topic (this should be the criteria to approve any session anyway) or because accomplishes one of the other criteria (top 50 karma etc) or both.

In practice: the content committee needs to look carefully what lightning talks get approved, specially when they come from someone "unknown" in the community or difficult to evaluate based on e.g. other presentations elsewhere.

Don't get me wrong. I'm overall happy on the selection of lightning talks and corresponding sponsored participants last year. But now I think that it was too easy to submit a proposal, get the corresponding sponsorship, deliver the 5 minutes and enjoy the weekend in Berlin. Maybe someone is tempted to exploit this "weakness" this year.