I've used my RTT now a few times, and although it has been fun, I'm riding the fence on whether or not I will keep it. There are a few more cons that I've discovered from the last few uses. They are:
1) Bulk. The thing weighs 120 lbs., is 7'x3.5'x2', unwieldy, and hence is a bitch to store. It's easy for a buddy and myself to move, but this weekend no one was around except for my wife, and she's tiny. We pulled it off, but she could hardly get the thing off the ground and it took ten minutes to get it up there.
2) Weather protection. I know it's not a cold-weather tent, but it's barely a two-season tent. In the summer, it's not opaque enough to keep out the sunlight. In the winter, it's too drafty to retain any heat. Late last summer, I roasted my ass off by 07:00, and last weekend, I froze my ass off until 09:00.
3) My family's needs. I have a wife who hates climbing up in the RTT (ladders + platform flip-flops = hell no), and a one year old son who I'd never let go up there. I have a two-person Marmot tent which serves my purposes for myself and a friend, and I have a full-size expedition tent that my family can stay in (furniture and all) very comfortably if the weather turns sour. Both put up in five minutes or less.
4) Surfboards. Can't put surfboards and RTT together, thereby eliminating the RTT completely for surf trips, which make up about half my ventures.
5) Can't just get in and drive away. Sometimes, late at night, when camp is already set up and some are asleep, we like to do a little "night 'wheeling". With a normal expedition tent, I'd have most of my camping gear in the tent, so I can just get in and drive. With the rooftop tent, I'd have to put stuff back in the bins, close and cover the tent, drive, then set back up when I returned. It's a pain in the ass, so I just opt out of night 'wheeling altogether.
Don't get me wrong, there are plenty of good reasons to have a RTT, I'm just not sure that it fits my needs at this point in time. My original plan was to mount the RTT permanently to an off-road utility trailer, thereby eliminating the need to mount it on the Cruiser, and having a permanent place to store my gear that I could just hook up to and take off. So far, other factors ($$$) have put that plan into indefinite suspension. I am now looking into paring my gear down, in order to simplify my operation, cut down on weight and increase efficiency and reliability. Maybe a conventional tent is a better choice for that goal right now.