Okay, hre's the deal
Some boats can carry a 150% genoa in huge winds (20+ kts), while other boats a 150% genoa in those winds would blow the boat over. It's basically a function of sail plan. If your boat is main driven, a 150% genoa would probably be too much. On a boat with a small main in the sail plan, the 150% would be may be fine for strong winds. So the answer is.......really depends on your baot.
On my boat, anything over 12kts of winds (apparent) with a 150% genoa would be too strong for efficient sailing; basically a lot of weather helm. I traditionally run a 135% genoa up to 17 to 20 kts of wind before I reef it. My boat runs poorly under main only when beating, but great when running. Under jib/genoa only I can beat pretty well at a good speed, but need the main to point 5 deg or so higher and a half a kt faster.
Most boats will do well with Genoas in the 115 to 140% range up to winds 20 kts or less, so if you have the funds, get something in that range and use it as your all around genoa and use the 95% as a heavy weather sail and the 150% as a light air sail.
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