Thanks for the comments. While I have absolutely no intention of testing any of the theories.
When I'm on my pontoon, I wear my waders, a wading belt up close to the top and a PFD that doubles as a fly best (mesh shoulders and back with 10 or so pockets.
I like the idea of the ones with the C02 cartridge but if one whacks his head on the way in, pulling the handle is out of the question. I'm not sure about the reliability of the ones that self inflate when wet (what happens when you're out fishing in a hard rain?). Also, when my life is on the line is no time to realize something has failed, some connection has become corroded etc. Guess I'll stick with the "always on" type.
When wading, I do my best to not go in water much deeper than waist deep even though I have chest high waders. If unsure, I probe around with my wading staff. General rule I try to live by "if I can't see the bottom, I have no business walking around in the water there".
However, accidents do happen.
It seems the general consensus is wear the belt fairly tight (not cut off breathing tight), be careful, and do your best to not panic when you float your hat.
Again, it's something we all need to be reminded of from time to time.