I also replaced my SilverGen after 8 years with the newest model. There IS an advantage with the faster stirrer. With the old model at max setting there would be the agglomeration droppings at the bottom of the jar until you dial back to 3/4 PPM. It also had an overly strong metalic taste at that setting. I went half like you and everything was fine.
With the faster stirrer (I guess) you can go full ppm with no agglomeration and without the heavy metallic taste. I now make everything at full ppm for longer storing.