The break even for the Voom package purchase depends on the cost in the planner, the cost on the ship and the length of the sailing. On ship prices vary, especially if the ship has done away with the Surf option. As you may have noticed, the planner Voom prices also fluctuate. For anything less than 7 days, you are probably better off buying on board with the D+ discount and no, you can't apply that to an already purchased planner package.