I can see where Phychicash is coming from, when your looking for a server "up" time is a big deal, if players on a server start playing about creating dormant RFTools dimensions and the dimensions continue to use server resources until the server is restarted it could become a huge problem.They stay loaded in the same session. If the server restarts they will be unloaded and stay that way until someone goes to them.
Is that the case and is Mystcraft the same in that respect?