For clarity I don't run the main and 160 in 30+...just an example to try to bracket in the sane limit for my boat.
I have four headsails. A very light 160(down wind "gennaker", maybe), a 153% Genoa, a 130% Genoa, and a 110% #1 jib(wraps the shrouds by 1' when pulled tight).
At what wind speed, approxamitly, would I use each head sail? When would I douse the headsail and go to main only? When should I reef?
How much heel angle is dangerous?
I am sure the boat is much more daring than myself and the GF is not scared of healing at all. Much to my shagrin...that means I have to admit I am leveling out the boat for me.
The boat sails well under main only. I have been playing with the vang and traveler. I find it much easier and faster to control boom swing with the sheet on the vang rather than the traveler.
Well it's a more complicated equation than wind strength. The short answer is, you reduce sail when you feel overpowered.
The long answer is, whether you feel overpowered depends on a number of factors :
Racing or cruising?
Solo or with crew (solo it's harder to release that jib sheet AND to shorten sail!)
Experience of you and your crew.
Gusty wind (lake) or steady?
How screwed would you be in a knock down or capsize? (distance from land, water temperature, etc)
Sailing solo in my centreboard daysailer in SF bay I am very conservative. I'd be in big trouble in a capsize. I just use the 90% all the time.
Racing with a couple of experienced crew in a stiff keelboat is a different matter.