I have the "family seat" option that consists of the miniature bench seat, two seat belts with inertia reel shoulder straps and the ultra useful footwell. I have used it once (only) and I have to say that it is very unnerving to fly the Sierra that close to the edge of the envelope, with so many souls on board.
Out of it all, I would prefer to ditch the seat and make good use of the conveniently sized hole in the floor for secure stowage aft of CofG and enjoy the flight. If I really needed the additional seating, I would look for a 300hp Bo.
Mark
In Oz