CTP (cost per thousand prims per month) is sorta a base line number you are right Nock. I think then you should understand features availble in that sim--like avatar loading, physics performance, level of detail (LOD) on mesh. But why would CTP be double on a void than on a full region? Makes no sense. CTP on an OpenSim is a lot lower still--but of course the features available are not the same as on SL.