I know the question is Troopy or Deli.....but......
I travel a fair bit with lots of gear and a couple of years ago was discussing the same thing with a friend, Troopy or Deli?
I wanted something that would go well offroad but that I could sleep in.
I was going to go the Troopy for the toughness and offroad ability.
I ended up just pulling the very back seat out of my seven seater Nissan and making a false floor setup that I could put gear under. So it is still a 5 seater normally then when I fold the normal backseats forward I can extent it out to make a bed.
I usually only have the swag or the mattress in not both as it had in the photo.
When I go on longer trips (like the 3 week NW trip that I just got back yesterday from), I remove the rear seats completly so I can fit an icebox for drinks inside one side door and the waeco for food in the other. Because the floor dips down where the seat was, I can access both with the bed still in place.
I think because of the accessibility due to the side doors it actually ended up working better for me than a Troopy would have.
My friend ended up getting the long wheel base Deli that we set up with a false floor/bed as well.
We also wound up the torsion bar front end and did a bit of 'modifiying' around the front guards with a grinder so we could fit some 10.5 x 31's under it.
It has acres of storage room inside and went extremely well on the trip.
We did a lot off off road stuff in some pretty boggy sand, and whilst not quite as capable offroad as my Nissan (which has a lift kit and 12.5 x 33's etc) it was definitely no slouch in the soft sand and it was only the clearance over the real rough boggy stuff that it struggled with.
As for fuel consumption we haven't done the actual figures but for example on one leg of the trip my 4.2 Diesel used 64 litres where the 2.8 diesel Deli used 50 litres,
I did have all of the boards on top and we were going into a strong headwind though.