To Each His Own
I considered the Transit and Sprinter and they are nice with the high tops.
In developing my land yacht, I had to first define the intended purpose, like where is it to take me? In my area, MO. AR. OK. and KS. I'm in the woods, there are height restrictions called tree limbs. 75% of the use will be in the mid-west. 25% on longer travels, campgrounds or stealthy stop overs.
Next, do I want to look like a passenger or camping van or do I want to blend in to the work force like a utility van......? Since I take a lot of naps, I don't want to pay for a motel for a few hours, so, truck stops, Lowe's, or in the back of some closed business, some delivery/work van won't be drawing attention. Sometimes the nature of the voyage will determine the equipment and looks of the vessel.
MPG? High profile vehicles will use more gas. I just don't believe the claims of better mpg with a custom top, then there are head winds and crosswinds already mentioned.
Now, a pop top could meet the need to stand up and nothing says your hatch must be open in very cold weather or some storm to go to bed.
It could also be hidden with a utility rack contraption when down. So does an annex door tent with a hard floor. There is always the utility trailer conversion gig too. What is easier to heat and cool, low or high tops?
It all depends on your real needs, there will be trade offs. If you must walk around going down the highway, consider a small motorhome. :coffeedrink: