PTWoody said..
Yeah I think the neck support thing is not very logical as a claim of benefit with inflatables because the first assumption is you are unconscious and can't keep your head up.
I'm no expert but I don't think that is the case. The support is so you can lean back and conserve energy floating with your head up clear of the water for a prolonged period.
I think the "instant unconscious protection' is a bit of a read herring (generally and notwithstanding Lacey's turn) because, if it was a primary motivation, we would all wear pdfs when surfing where there is far greater danger of getting smacked in the head or having a heart failure paddling out / for a wave etc (or suit up in F1 protection gear every time we get behind the wheel).
Instead methinks it is primarily to provide a layer of safety when, forever whatever reason one is stranded (i.e. cramped up or flat out fatigued) and/or getting blown off shore and perhaps facing a night on the water (i.e most likely situation?). That situation doesn't require "instant" pdf floatation.
In that situation, and sitting on my board (assuming that my well maintained and fitted leggie is secured!), faced with the choice of a pfd or an inflatable belt with head support, I'd take the latter.
Genuinely interested in hearing counter-arguments and if a pfd would be better because I've considered upgrading the pfd I've already got to a better model but think that if the brown stuff truly hit the fan (sudden unconsciousness aside) I'm better off with an inflatable.
Perhaps there is a pfd out there with an inflatable head support option which would cover both options?!