[Jeff_H]

My sense from sailing on and against assymetrical spinackers is that unless you are sailing a very light weight easily driven boat that can really make big gains by sailing hot angles and scalloping down in gusts, your VMG will actually drop with an assymetrical spinacker vs a symetrical chute. So you are taking a 3 sec a mile hit for a sail that may be costing you more than than in downwind VMG.

Jeff