I've got an Astral Norge its a kayaking pfd. It uses a different kind of filling. kapok (sp) it's really soft. I don't know if it hold you face up but all the boyancy is really high, and it sits really close to the body. It's like wearing a big hug all day. Clears the hook on a harness well. I would think the less complicated the better.
No self Infalting device!!! That would be funny tho! First big wave and POOOF! Here is my Logic or lack there of! After trying all of our old Hobie jackets, Musto vests and a brand new MTI Orleans kayak vest none of them would float me face up!!! The MTI was the best with all its flotation hi-on the chest and very thick at chest. The MTI was great paddling but sucked for getting on the hook. In flat water it would not roll me face up! Once on my back it was pretty good at keeping me there! So if I had a normal Class III Pfd of this type and get knocked out! all they are going to find is a body in a nice jacket, UNLESS I was lucky enough to land on my back! As I mentioned before I am having seizures that come on slow and leave my left side worthless! So I am hoping that if I have one on the water I will be able to pull the rip chord have my fancy jacket inflate to 23.5lbs!! that will give me enough time to chill and wait for my body to come back! Yes I will have to test and maintain the Co2 device for all of this to work when needed. So that's my theory at least! If I do come across a jacket that I can sail in and will save my butt, then i will get it! It's only money! Right???
No Coast Guard Type III PFD (the kind most of us wear) or Type V (inflatable) will float you face up when you're wearing a trapeze harness.
ISAF Rule 43.1(b) says (in part):"A hiking or trapeze harness shall have positive buoyancy and shall not weigh more than 2 kilograms, except that class rules may specify a higher weight up to 4 kilograms."
So where is most of this "positive buoyancy"? On your butt.
Try floating relaxed in a swimming pool dressed in full gear. The stable floating position is face-down, butt up.
I have heard some folks talking out of their A** and that might be where they breath as well! Butt seriously!! If I was not having issues I would have one of the minimal jackets with flotation lower! they are great for kiteboarding and kayaking! especially when you are trying to get your head above the surface when floundering! It's like sitting on one of those foam noodles! not much there but really helps one float hi. At least that's my take on it!