It was hugely helpful for me to see both in person, see how they open and close, set up time, crawl around each and imagine how I'll use it.
I was 95% sure I wanted the habitat vs the J30 until I saw both. The space of the habitat is amazing but to me it was a lot more setup/breakdown, it's all tent which sucks in rain/snow/cold, getting the top to latch was tough, there were a lot of opening and gaps and such. Plus there is the obvious downside of not being able to use a roof rack.
I crawled into the j30 and it felt pretty comfortable, well sealed, it was only about the size of our small tent that we use but the vertical side walls vs the dome of our tent makes it much more tolerable. I could flip up a panel and stand up, access gear stored downstairs, etc. Setup and break down was easier and quicker, and there is plenty of room for solo trips and sufficient room for my wife and I. We really don't need/want to "hang out" inside anyway so I think it should work well for us.
And again we don't stay put much, we move around a lot and I didn't feel like I'd want to setup the habitat for a quick sleep. With the j30 I would leave sleeping bags upstairs all the time and could quickly pop it open and crawl in for a nap or whatever, and not be too concerned about packing it away during the rain since there isn't as much fabric to soak up water.