I have two of the old, old Stearns float coat jackets I bought in the late 80's/early 90's and they are still functional today. They are a little stiffer than they were when new, but they are holding up well and I still use them when it starts getting really cold. They are the perfect thing to wear when running big water in the dead of winter, but I do not hunt with them on as they are too bulky.
IMO, anyone who spends time on the water during the dead of winter should consider a float coat as part of their equipment.