OK, this might depend on the plaster material. I did some trials with an acrylic plaster material called 'Jesmonite' and I really could not distinguish between castings made into the same moulds, other than by the weight and colour of the items! It worked best when the moulds were put into a pressure pot and held at 60 psi until the plaster had set, but the surface quality was just as good as the polyurethane castings done, under a vacuum, in the same mould. Dental and building plasters may be coarser in texture and that might prevent some of the finer details in the moulds being resolved. I'll dig out the test castings I did and post some photos.