I have also read that a drysuit could be quite a hindrance if one is submerged - a bit like an inflated life jacket. I know one can let the excess air out by poking a finger down the nect/arm seals but someone in this situation won't have time for that.
You expel the excess air before you get into the aircraft. I did the RAF Sea Survival course a few years back, exiting the a/c was not covered as it was assumed one had banged out. A few points:
Warm spring day, moderate swell, English Channel off Plymouth, wearing bone dome, immersion suit with integral boots over long underwear, thick kneee socks, T-shirt, flying suit, leather flying gloves.
Maneuvering in the water with inflated life jacket, combined with bit of bouyancy in suit is not as easy as swimming
It was a struggle to inflate dinghy, tugging on the lanyard just kept bringing dinghy closer. Solution, both feet on dinghy pack, pull lanyard. Dinghy inflated inverted, easy to right it but I suspect it would be difficult in any sort of wind.
Boarding dinghy, get top half of body on take a breather, haul rest in. Get canopy up & bail dinghy out asap, inflate dinghy floor asap, put out drogue for stability.
Figure out if its better to activate emergency beacon immediately or save battery life and wait until you know SAR willl be looking. (This was before sat beacons).
Even though it was a mild late spring day I got cold v. quick. Leather gloves get wet & slimy and with cold hands its hard to do fiddley things, get kit with big Fisher-Price type knobs & switches. Have water, you'll be thirsty as you are bound to get a bit of sea water in your mouth. Ditto sweets/choc for an energy boost/morale lift. Have a woolly hat to wear, stop head heat loss.
Can't remember the exact advice on flares etc sorry, cept keep till you expect SAR to be searching except if obviously, passing boat etc.
Water activated strobe lights v.good.
Lastly, underside of a yellow heli is a beautiful sight after an hour pukeing into ones lap.
