George, your post caused an explosion to go off in my head (I would have said "bell" but the reaction was a lot bigger than that). This post reveals more ignorance about rigging than I'd like to admit, but here goes:
I have roller furling for my genoa. I removed the sail for UV replacement. A brand new jib came with the boat when I bought it last summer. The jib is in a bag in my garage. When I removed the genoa, I assumed I'd be out of commission for a while without a headsail. After reading George's post, it occurred to me that I might be able to use the jib by simply attaching it to the furling drum and raising it with the top part of the furler system (which, of course, is down at this point) and raising it with the same halyard. Am I making a correct assumption?
Another question: I've never raced, but have wondered how a boat with a furler system could change headsails under racing conditions. How's that done?