Now, you get into philosophy, Bob. The basic instructions for casting resin say to mix it up and pour it in your mold - no mention of pressure or vacuum. Then, you have the pressure or vacuum camps. There are arguments both ways.
I should have clarified about my HF pot. I re-plumbed it to have both vacuum and pressure connections with a ball valve to choose which way to go. I use pressure for acrylic resin and vacuum for stabilizing. Since setting up the HF pot, I got a 1.5gal glass jar to use with vacuum for stabilizing so I can see when the bubbles stop coming out of the material.