Mine's in the bubble right now, but if it wasn't I'd have it on a jack. Most jacks have the prop rods to prevent the jack from letting the bike all the way down if the cylinder loses pressure.
I have mine on a jack and like others said it helps with flat spots on tires. I do not worry about the jack at all it has the safety hinge that locks in should it loose pressure I have read it many times that off ground is best also I change my oil when I store the bike its a good idea.
If you read your service manual, it clearly states to raise it on a lift with both wheels off the ground for storage. I have a cheap chinese pos jack I keep mine on when I'm not riding it.
Don't have to worry about winter storage in Florida, but when I lived in the frozen tundra, I did not use a jack. I did, however, over-inflate my tires for storage. Just remember to let out some of the air before that first ride in the spring! Also, a center stand is a good compromise for a jack if you are worried about the jack failing, but need the bike upright for more space in the garage.