I think the decision on headsail changes is based on the use of the boat at the time. As an example if I’m racing I will keep my #1 up in winds over 20 knots but when I’m just playing around or heading out for vacation I would drop and change to a #3 in 20+ knots. The same logic applies to reefing the main or reefing a furling headsail. I guess what I’m saying is that I can’t opine on your question without knowing some other information. What are your current sails made out of? Can any of them work on your furler? Do you race? Do you have a furler that you can reef? How much heel can your boat take without going sideways or becoming unmanageable due to weather helm? Do you have a crew?
Every situation demands a different sail plan and a different set of guidelines. I would hate to see you buy another sail that you don’t need or buy one that you won’t ever use just to have it.
“Greatness Is Not In Where We Stand, But In What Direction We Are Moving. We Must Sail Sometimes With The Wind And Sometimes Against It – But Sail We Must, And Not Drift, Nor Lie At Anchor.”
Oliver Wendell Holmes