The red rectangles areas on the Front and Rear P-Q curves represent consuming horsepower when merged. On PC200-7 , this is an example , when the front pump pressure becomes very high like 300K, the both pumps pressures becomes 300K at the same time. On PC200-8 by dividing Front and Rear pump lines, independent PC control is done and the area of the yellow green rectangle represents reduction of the merged loss.
If the bucket lever is operated with full stroke, the maximum flow rate can be increased to enable faster movement of bucket. So this system is not only to save fuel consumption but also to realize faster cycle time.