I have not switched to a ground tent yet, but since my kids are getting bigger, I've been seriously contemplating an OZ or Springbar style tent. I flip back and forth as to whether i want to go back to sleeping on the ground, on some trips I think it might be easier, but on other trips I'm glad to have the RTT. For the price, the ground tents definitely have an advantage when it comes to interior space and weight. Also, there are times I wish I wasn't anchored to the campsite because of the tent on my car. But everyone has different priorities and styles of camping, so there's never one right solution.
My main priority is speed and ease of setup, since I'm usually rolling into camp late at night and setting up in the dark. I think a RTT (especially the hard shell ones) probably have the advantage here, because I can camp anywhere I'm able to park, I never have to worry about finding a flat, level site large enough for a tent. There were some sites where setting up a large ground tent would be cumbersome. It's not so much the tent itself, but all the pre-setup (clearing the site, unpacking the tent, etc) that needs to be done before setting up, then the post setup (staking it out, putting all the bedding and mattresses in) that really add a lot of time to the actual setup time. And I'm not sure how some of these large tents can handle high winds, there are times where winds suddenly pickup in the middle of the night after I've gone to sleep. Do people always stake out their ground tent every time? How do they handle the wind you can't stake it out?
The other reason I have hesitated in getting a ground tent is because the packed size for some of these tents are huge. I think the OZ tent is over 6' long when packed, which means I'd have to store on the roof anyway, negating some of the advantages I was hoping to achieve by switching to a ground tent. Putting a RTT on the roof is a pain in the *** no matter which tent you have, but at least it's usually not done very often. Even though these ground tents weigh half as much as a RTT, having to lift it up and take it down each time would get really old, really fast.
The biggest variable in setup for a RTT is the mounted height of the tent. On a subaru, setup is a breeze, I can park the car and be sleeping inside the tent in about 2-3 minutes. On a lifted landcruiser, it's like a combination of rock climbing and parkour, you really need to be comfortable climbing all over your car. It can take up to 10 minutes, but the good thing is that it's pretty consistent regardless of weather or terrain. Even though the mattress and some sleeping bags can be stored inside the tent in the closed position, with the whole family I've never been able to fit all the bedding and pillows and extra clothes needed. What I do is mount a small roof rack right in front of the RTT where I can store all that stuff in action packers, so I can just reach out the front and grab it.
My family loves the RTT, because there is some added sense of security to being on top of the vehicle, whether it's real or imagined, it doesn't matter to them. If it makes them more comfortable and allows me go camping more often, it's worth it. Kids just love RTT because it's cool, there's something special about sleeping up high, the kid in me agrees. For solo camping I'm probably indifferent about ground vs roof, but if I did a lot of camping by myself I'd probably skip a tent altogether and just find a way to sleep inside the vehicle.
and off course I still have my ground tents.
