Premixing ingredients is unnecessary. There are no dangerous augers to get caught in, no sharp blades to cut and no high speed parts to avoid. Shipping weight 500 lbs. It is never lifted against the force of gravity as with blades or paddle mixers. Soldner mixers are made of concrete, which when wet, release the clay.
Most mixers chop or squeeze clay with multiple blades.
Soldner mixers cut and rotate it in a single motion, spatulating and blending the mix continuously. Use the tub for clay storage. Slake your trimmings, make it your slop barrel or store mixed clay in it. Replacement parts are standard off the shelf items. Most mixers are still in use after twenty years.