next best thing to a KD21 system
Now I may be partial here,(no real suprise!) but it is a variation on a theme on a design that Hobart had beginning with the 21 series. I will stand corrected, but I am nearly 100% sure Hobart had the idea of separating the soils into a holding chamber and then washed it down during the drain period by reversing the motor before anyone else brought anything like it to market. The major difference was the all metal drain impeller which acted like a miniature garbage disposer and ground up everything that got that far down into the water system.
After the 21 system, I would take the Power Clean module system as my second choice for great cleaning systems. As a point of fact, after Whirlpool bought K/A, they introduced the power module into the K/A 23 series machines which were relatively short lived before the 24 series came out but still used the power module setup until the tall tubs came out with the horizontal pumps.