" The efficiency of a symmetrical spinnaker is not worth much if you're finding it too much work to make it worthwhile to hoist and fly. "
SD - what about the feeling of satisfaction that comes from a good downwind leg sailing deep, accomplishing a couple of gybes without disaster? We find it very rewarding at the end of a good spinnaker run, even, and maybe especially, when cruising.
Where we sail the wind tends to follow geographical terrain, so we often end up either beating or running. A long day downwind reaching can be shortened up considerably sailing deeper. Here we "need" the symm sail.