Since the beginning of the Adirondack 90-mile canoe race, for the first 35 years (before the Northern Forest Canoe Trail acquired the race), PFDs had to be carried, and encouraged to be worn, but were not required to be worn unless weather and race officials so dictated. With up to 275 boats in the race, along with numerous volunteer and DEC official safety boats all along the race route, it was not a requirement to wear your PFD. I do recall seeing several "pro boats" (very fast, but inherently unstable) overturned when afternoon wind and waves kicked up on broad downwind stretches of Raquette Lake. It was always at a particular commonly windblown shallow area rounding a bend next to shore, so there was ready self-rescue or assistance from other nearby passing boats (a rules requirement of fellow racers). Since then, the route has long ago been changed to avoid that area. After NFCT takeover, due to insurance and common sense necessity, it is now a requirement wear a PFD at all times, but inflatables are acceptably legal.
Of course, on the Yukon River races, the water is glacial melt temperature (<40F), the river is mostly smoothly although fast running at an average speed of 6 mph in most areas, though there are a couple of sections of much faster water with rough tall standing waves and tricky currents, though no real white water. 35 miles on Lake Laberge is often stormy and can be very windy pushing large deep trough rollers. Therefore, we are required to wear our PFD 100% at all times on the races and to remain closer than 200 meters from the eastern lake shore. Too far to swim in rough cold water IMO, even with a PFD given conditions I have experienced near that limit.
I use a Kokotat Orbit model as one of my several choices of PFD, which has a couple of pockets necessary for carrying a list of required emergency safety gear on my person during the Yukon races. Since I took a state swiftwater rescue techhicians course, I have purchased a Mustang rescue grade (25 pound buyancy) PFD that I would use for SAR rescue incidents, but not for general recreational or race use.
If you want a real test of PFD use (or not), try a controlled warm water capsize without wearing your PFD, and then try to put it on while swimming in deep water. Doing so reminds me of a famous Mark Twain quote: "A man who carries a cat by the tail learns something he can learn in no other way."