With my most recent eBay purchase of an asym. spin., I completed my inventory of 11 sails for cruising (boat came with 4, all purchases were used sails):
1 Large symmetrical spinnaker
1 Small symmetrical spinnaker
1 Large asymmetrical spinnaker
6 Jibs: #1,#2,#3,#4,#5, and storm jib
I bought the asymmetrical for those days when the wind is at or forward of the beam and light to moderate.
I should be able to sail well on all points, upwind when the wind is about 5 knots or higher and downwind at about 10 knots or higher.