I did not like having the gray water line feed into the black water discharge port for a pop-up camper situation. There is no on-board gray water holding tank, so I have to use a blue tote connected throughout the camping session. The black tank occasionally, essentially turning my blue tote into 17 gallons of black water. It's a relatively simple process to clean the blue tote when it is just gray water. Being contaminated with black water adds complication I do not want to deal with while in the field.
I cut the gray feeder line into the black, put a rubber cap on it and installed a separate discharge port next to it. I like this much better. My only overall improvement would have been to have a cassette potty instead of an actual black water holding tank. I have to get in line with every other trailer at the dump station on pull-out day.