Running my own instance is a bit heavy just to try the platform :). But thanks for the tips, I can create draft and delete them without trashing your instance.
The fact that it is open source is a major positive point. I suppose you have heard of SJS [1] which in a way is very close to what PubPub is, except I do not believe in SJS because of it being closed source: it is way too unsafe for a scientific community to take the risk of adopting such a media for a new journal or a conference as the platform is not open and there is a risk of Elsevier buying it to shut it down or closing it even more, for instance.