Stress
I think everyone missed the point of your question, John. I took it to be a question about flying a jib alone with no main up in very strong winds, as opposed to flying some or all of the main with no jib as it relates to the stress on the forestay. I have heard pros and cons about that as well, with no real good answer to either question. I was told by an A.S.A. sailing instructor that the headsail has only one attachment point and thats near the top of the mast. All the drive from that headsail is borne by that one little forestay connection at the masthead.With reefed main, the sail is attached to the mast from top to bottom, spreading the load on the whole mast. Seems to make sense that a reefed main, as far as stress loading goes, distibutes the load on the whole mast not just one connection point as does the forestay. Tuning and sail balance is important for how the boat sails, but what we're really talking about here, is stress on the mast. I reef main first, headsail second and balance the two. Hope this helps.