Hi Troy,
The first two boats to have self tacking jibs like is growing popular today were the RC27, 1983 and the ARC22 1992. These boats have the mast well aft on the boat. The 27's mast is 12ft from the transom and the forestay chainplate is 6ft aft from the bow. The very first 27, 1981, had a conventional jib system with fairleads on a wire about 3ft aft from the main beam. When I put a spinnaker pole on the 27, I saw the opportunity to lower the foot of the jib to the spin pole, deck level, and gain jib sail area down low and increase jib luff length below the old high footed jib position. The loss in jib area was along the leech. The net result of these two jib area changes was a small loss in total area. The gain in luff length and forward jib area far outweighed the loss in jib leech area. The boat was faster with the slightly smaller jib of higher aspect ratio and longer luff.
Bill