Great post! I wear mine when I’m in my float tube, frameless pontoon, drift boat, and 16 ft motorboat. I haven’t heard the case of tangling with fly line but see where that could occur. I won’t launch the drift boat or motorboat unless my passengers are wearing theirs. None of my fishing buddies have protested.I've been float tubing for 35+ years and have only seen two guys flip their float tubes, both occurring at Dry Falls Lake. One guy was trying to untangle his fly line that had wrapped around his fins, and he flipped over forwards. Fortunately, he was near shore and was able to extricated himself without drowning. The other guy was a friend of mine who was out in the middle of the lake releasing a fish he had just landed and his fly rod fell overboard. He reached over to grab it and flipped over sideways. Fortunately, he was able to extricate himself quickly and swim to shore, losing just his anchor and cellphone.
Several years back I was up at Big O.K. Lake in BC, and I saw all these emergency vehicles on the northeast shore, so I went over to investigate. Turns out another fishermen (fishing from a pram) had drowned, apparently by falling overboard and getting tangled up in his fly line.
I always wear a PFD, no matter what and so far so good. When someone goes fishing with me, I always tell them to wear a PFD, but that if they are going to drown themselves, please have the courtesy to do so at the end of the day so as to not interfere with the good fishing.