In article . net, Mike
Rapoport wrote:

It adds more weight than you might think. The area around the door has to
be reinforced. Make a paper box and feel how stiff it becomes when you tape
the final side and then cut a jarge hole on one side and note how much
stiffness it loses.

I understand the torsional rigidity issue.
Cessna does it, suspending the fuselage from the wing.
Beech did it with the Musketeer line.
I would think the wing on the bottom would make it easier because the
wing center section spar box and not the fuselage structure is not
carrying the load.
How much weight are we talking about? 25 pounds?
The weight's of Pipers and Cessna's seem pretty comparable across the
product lines.

Is the question more one of economics?