Kitehard said...Hi Fooosh,
I wouldn't wear a bouyancy aid of any type in big surf for the reason it will have enough floatation to get you above the water but not the white water/foam which you also can't breathe.
Without the ability to duck the sets you may be swept along on the face of the wave but underneath the foam. Pretty strong chance of drowning.

Totally agree with kitehard..........
But how big are we talking ?
But in the comes down to personal preference......... and individual situations ie: how far out ? do you have a boat on standby ? How strong are the sweeps ? Where is the closest out ? Is there a chance you will spend some hours in the water if something does go wrong ?)
Foosh are you the sort of person who knows what they are doing in big surf, I guess I am asking are you a confident water user surfer etc......If you are capable and can duckdive, hold onto the bottom etc........ I would not be wearing one at all. If you are not confident in that kind of situation and are most likely to just bob around and wait for the swell to push you to the beach WEAR ONE.
PHOTOGS spend all their time in the impact zone and I have never seen one wearing a PFD or floatation of any kind other than a wettie, this is because they know what they are doing and use the subsurface as a safety.
If you are talking waves over 15ft sorta thing remember when it breaks there is about 4ft of airated water (whitewater) before you reach the surface a PFD will not float in this and as kitehard said you still cannot breathe ( nor can swim down if you are wearing a PDF or similar you are in limbo ).
That is my experience but if you are not 100% confident Wear ONe
Floatation devices do make a body retrieval easier.