Many of the modern integrated instrumentation systems can display this data, or you can use a set way-point to windward on a GPS to come up with the number. By using a cockpit-operated snuffer, no one has to be on deck when the spinnaker is flying, being jibed or doused. To jibe, simply let off one sheet and pull in the other. Downwind VMG is doubled. Less motoring and more sailing.
Wind gusts lift the bow, propelling the boat forward with finger-tip control.
Speed from the asymmetrical's greater power pushes the apparent wind 30-50 degrees forward of the true wind direction. In light air and lumpy seas, the sail's added power steadies the boat. The new Js instill a sense of confidence, freeing one from anxieties. There's less work. Guests aren't pressured into unfamiliar tasks.