Interesting. Acme Plastics, a large distributor, says the opposite.
Extruded acrylic costs less than cast and is more dimensionally stable, meaning the thickness is more consistent across sheets. Softer, with a lower melting temperature than in its cast form, extruded acrylic is easier to laser cut, rout, and polishes more cost-effectively … Extruded acrylic is less susceptible to dirt, lint, or particulate contamination in the production process. Additionally, because of its lower melting point, it is better suited to cementing and thermoforming.