For the past 38 years, my venue would have 61 degree midsummer, and 48 degree winters water temps with an average air temp around 59 degrees.
90% of windsurfers wear a sealed 4/3.
Not cold, just moderate.
I've broken over 30 masts, 15 booms, 6 boards [3 cleanly in half, the other 3 shearing into two pieces on the way to shore], a dozen mast bases, and several inhauls.
Easy credited with 15+ rescues of other sailors at Crissy Fields in SF.
Anything worthwhile?
Not for you.