Having had both and new old camper having only black tank and no grey tank the gray water had been more of an issue. Where and how to haul the 22 gal. gray water filled blue tote tank was the issue. Most places frown on letting gray water out on the ground nowadays. That's why I moved the spare tire to front of truck and modified and flipped the blue tank and mounted it under the truck. Now both get dumped at the dump station nearest to where we camp. Many campers with cassette toilets have little to no grey tanks. The hard side pop up A frames are among those, had one, hated it.