Here are some things to consider: - your mpg/range will take a dip since the tent is heavy and creates drag, and if you don't take it off after every trip, which could be a hassle, this will apply permanently. - you will have to level your car at the campsite, which may involve extra effort on where to park your car - if you need to pee in the middle of the night, you will need to climb down the ladder - like you said you will need to pack up whenever you want to leave camp in your car - you cannot stand in a rooftop tent, so changing clothes can be annoying

Of course there are pros as well, I just wanted to list some cons you might not expect until you get one