I always manually inflate the harness/vests every year--if they don't hold pressure overnite, its off to the rubbish tip (and some have gone).
There is a downside to wearing the big life jackets, and even the vests if you load them up with gear. It makes you more awkward and more likely to go over the side. We had a 150 lb crew go over the leeward lifelines with a non-inflatable lifevest full of strobe/handheld/gps stuff and it took four strong guys to get him back on board because all that stuff got hung up on the lifeline--we had to lift him well clear of the top line to get him back aboard.