Not all BC's can be made autoinflate, unless you've got some inflator that just happens to match a standard CO2 screw thread. I don't.
Mustang seems to have taken a page from BC design, i.e. the lower down you put the air pocket--the more chance that it actually translates into bouyancy. Took 'em long enough.
Brak, if you think a PFD resembles a hangman's noose...try the vest that is packed under every airline "overwater" seat. Nuh-uh, if I ever need to use on of those, it ain't going around my neck no matter how nicely the stew begs.