Well I have a couple of different modes for my van.
For stealth camping the cab blackout curtains are drawn and the other blackout curtains behind dark side windows. And I use blue or red LED lighting inside which means no chink of light has a chance escaping. But I only have two seats round my lounge table then. It's fine for one or two. I guess your equivalent would be roof down and blackout sleeping on lounge/van seats.
For site camping or friend's drives or places like Stonehenge, I can swivel the seats, put up silver screens etc. This makes it obviously camping, but I can have a four or five seater lounge and much more space bringing the cab into play. You could use your roof for sleeping and storage while having the space below exclusively for cooking and eating.
So with an elevating roof you would still have a choice of stealth or spread out whereas with the demountable you would just have campsite mode and lose the looks of the vehicle somewhat. Although you can still wild camp in a demountable no probs but I camp a lot in urban areas sometimes in residential streets so I prefer a very low profile. It just depends where you park and what suits you really.