I worked for many years making toy soldiers (pewter D&D, knights etc) which were all spin cast (12" molds). We made a few production molds and timed spinning -vs- my aluminum 1 cavity molds - I was pouring 5/8 & 1/4 walleye style heads. There was no difference in casting time. What we found was the spin cast molds took time to 'load' with hooks & did have a quicker over heat time (so we had to let the mold cool) canceling out any extra time savings. If you have someone helping load, as mentioned above, you have just doubled your labor cost and would have similar results if you had two pots w/ two people pouring. As a manufacturer if starting from scratch I would start with everything spin cast (Im 2nd gen family jig business started in the 60s).