I find that when I'm starting to get concerned about putting up the chute but I do, the boat smooths out and becomes better behaved with the spinnaker flying. Granted, this is up to a certain point where you still have some ability to head up and down in the waves.

You'll also find that with the additional speed, gusts (especially if sailing on a lake in heavy air) approach you more gently while you have the spinnaker up and give you some additional time to react. If you are moving slower, the gusts hit you faster giving you less time to respond. That being said, when you do finally crash and burn with the spinnaker up making 20 knots, it's a bit more exciting than without it doing 16.

I expect to get a year out of a spinnaker before it is semi-retired to backup status...I do about 18 regattas a year.