The upwind and downwind sailing ability of a multi-mast rig
will always be limited (to one degree or another) by the turbulent downdraft interation between one sail and the other. With headsails this is mitigated a little by the slot that is formed between the two sails, but in the absense of any overlap, the downwind most sail operates in a comparatively turbulent environment in the downdraft of the more windward sail.
Some years ago, I had an interesting conversation with Olin Stephens on the topic of why the schooner rig
became so rare. In essense, when the upwind and to some extent downwind performance of a sailboat was limited by the inefficiencies of the hull and keel forms, and the stretchy nature of early sail cloths, the schooner rig
made perfect sense since it was not the inefficiencies of the rig
that was limiting the boat''s performance. It was only over time as hulls, appendages and sail cloths improved that the schooner rig
became the limiting factor in the performance of the boat and so fell out of favor.
So why would someone build a modern schooner? As has been said, it is a visually beautiful rig
. As boats get longer, split rigs
begin to make more sense. Also as boats become longer, it is harder to justify the kind of draft that would be necessary to allow an 85 footer to really point well. So with the use of a shallower draft than ideal for pointing efficiency, the relative inefficiency of the schooner rig
may be less of a liability than the shoal draft of the keel. Those would be my guesses.....