Personally, as my over-water flying is limited to the Mediterranean (mostly Adriatic) near the shores, I consider life vests sufficient.
Sharks?
The pilot who ditched in the Med was surrounded by sharks.
Why would you overhaul life jackets?
Same reason as a raft. To check for corrosion, etc. I am sure somebody who knows the system could just do a visual check, for nothing.
I recall life jacket overhauls cost similarly to buying new jackets, however.
Sharks?
I think shark attacks are extremely rare in the Med, even more so than in other seas. When I did my Croatian motorboat licence, there was absolutely no word on sharks.
Where happened the ditching you are referring to?
Pretty unlikely to be attacked by a shark in the Med....earlier this year 5 beaches were closed on the Costa Blanca when someone got bitten by something....eventually it was determined that it was not a shark attack....but if you're really worried buy one of these....
I have this from the TB20 pilot who ditched in the Med - with his agreement to post it
Yes, definitely carry a life raft. When I went in, I only got my feet wet, until the chopper came and sprayed sea water all over! And being in a raft is so much more reassuring. Where I ditched, the sea is very deep, 1400 feet sloping down to some 10,000 feet. There is a lot of big fish and when I saw a big white creature lurking under the raft, I was mighty glad my legs were not dangling like bananas waiting to be plucked. OK, I don't think it was a shark, looked more like some giant ray because it was wide and moved slowly, but sharks have been seen in that area. This one was caught in the same area, near Filfla.
I always used to keep the raft behind the right hand seat, handle up. In hindsight, one other item I would carry is some form of helmet, space permitting. One thought that flashed through my head at the time was if one wing catches a wave and the aircraft spins round, my head would meet the left door frame rather abruptly, possibly knocking me out.
Re PLB, I prefer to carry it on my belt. That way it is with me irrespective of what happens. The lifevests I had, were passenger aircraft type. You can inflate them slightly before you touch down and top them up easily if the CO2 cartridge fails. Never had them serviced. This servicing business for life vest/rafts and fire extinguishers is one big racket most of the time.
Ditching does not have to be any more dangerous than an off-field landing. Imperative that you touch down parallel to the swell. Do not fight it, let it settle down in its own time. The last few feet seem to take very long. You'll be skimming along in surface effect for what seems like a long time. Then the crest of a wave will rise to catch the bottom and it will feel like engaging the cable on an aircraft carrier. Big advantage for low wing, retractable u/c configuration. And plenty of dihedral helps too.
Quoting Peter
The pilot who ditched in the Med was surrounded by sharks.
and then
OK, I don't think it was a shark, looked more like some giant ray because it was wide and moved slowly, but sharks have been seen in that area.
In the end it was probably a goldfish. You should apply for a job at Daily Mail or the SUN 
I was repeating my recollection of an earlier version of his story, from nearer the time 
I have the same as Peter and AeroPlus. Took it into SES for service in Jan 2011 and to SERVICE, MAINTAIN AND OVERHAUL cost £55, Co2 Cylinder DTI test, Overhaul and Refill cost £88.67 all plus Tax. The interesting point is, when I took it in, they asked if I wanted to see inside, I never realised that the canopy is held up by a inflatable prop which you have to self inflate. They also gave me a menu of items to choose, to be packed inside, including shark repellent. You can take your own items to be packed.
As I have only two seats, I am considering getting two of these instead http://www.ses-safety.com/pdf/ELITE_HELP.pdf - do you think they will be easier to get in?
What is the procedure for getting into the single person liferaft?
I mean, apart from the trivial case of laying it out on the wing, climbing into it, and waiting for the aircraft to sink under you. That is the preferred way for all rafts, but may be harder with the single person one (into which you need to climb in the right orientation) than with the standard "square" 4-person one (into which you climb in in any way you can and it will be OK so long as it was the right way up).
From my home, 15 miles from RAF Lossiemouth, I've seen a RAF guy trying to get into a one-man liferaft in a choppy sea. Every time he got in, he soon capsized. It took him a long time to get the hang of it. Then the helicopter winched him up. It then lowered the winchman, and he dropped into the sea about 10m from the raft. A few swim strokes to it, first attempt he was in, and he stayed in. The helicopter went off, leaving him to drift ashore to the recovery team. It needs practice, even for a fit, trained, young, person wearing a survival suit, and knowing there's no danger.
Is it the case that marine liferafts default is to inflate, while aviation liferafts fail by venting? An accidental liferaft inflation in a small aircraft could be a problem. PS I wear a standard marine lifejacket on most flights. I did once manage to inadvertantly catch/pull the toggle and inflate it. No problem with lap/diagonal seatbelt.
Every time he got in, he soon capsized
I too can't get my head around how to get into one of those one-man rafts. They are very obviously unstable until you are well inside them.
The normal sort of "4 person" raft is also difficult to climb into. If you just try to climb in, it will simply tip back on top of you, and then you have the big job of pulling it right up. Soon, most people are going to be exhausted. There are two procedures I can think of which work; the easier one is to bounce yourself up and down a few times and on the last bounce you end up with your upper body in it, and after that it is doable (for a reasonably flexible person). I have tried this in a pool, which is obviously a much more benign environment than the open sea.
One would try to get at least one person into the raft, over the wing, and once that person is in, the raft is stable and also will not drift away too quickly. Whereas with the one-person raft each person has to get in on their own, without help.
Years ago I tried to buy some of the Switlick life jackets, because they are well made and properly padded around the neck. A lot of people who end up in the water end up with neck cuts from the standard cheap 50-quid aviation jackets. I could not get Switlick to communicate at all, but I think they now have a UK distributor.
Is it the case that marine liferafts default is to inflate, while aviation liferafts fail by venting?
I was told by one service firm that the aviation rafts are 99% likely to work OK. The most common failure modes are apparently either corrosion of the components (so it won't activate when you pull out the cord) or a crack in the rubber (it gets cracked after many years; the rafts do not have an indefinite shelf life).
