I have used the Lester system for about 8 years and recently used Hydro-stone to cast the bats. I have cracked one of the #1 plaster bats throwing ~12 pounds of clay down, but I probably had something under the bat. I have had two of the plastic "pin holes" break out of the plaster and therefore recently tried Hydro-stone. I think the plaster bats dry somewhat faster but have been very satisfied with both. After casting the bat I do bevel the entrance to the pin hole a bit more to make it easier to get the bat over the pins. They stay centered , have a very smooth surface against my hands and I have not seen anything suggesting plaster in my pots.I cast them on Formica sink cut outs that you can usually get for free from a cabinet shop,producing a very smooth top surface.