I was involved in some sea survival research for Plymouth University. One of the tests was to dump teams of 1st year undergrads into open water holding on to a fully inflated raft and see if they could get in. All the ones who had a member with previous training did, all the ones with no training failed. Now this is quite an optimistic result as the students were expecting the exercise, had all been briefed and were only in light clothing, did not have to get out of an aircraft and inflate the dingy. It was summer and the sea state was good.
At my strip we have an ex RAF guy who was involved in rescuing ditched pilots over many years and who has watched from above as several crews fail to get out of their aircraft at all, let alone get out with a 25kg lump. His take is that getting out of an aircraft with a dingy is very hard, and that getting in a 4 man dingy in average open water conditions would be impossible for Mr Average. He recommends an immersion suite and a 1 man dingy each. His theory is they are light and small to get out of the aircraft and very easy to get into. Each person needs their own PLB.
I did a lot of open water survival stuff many years ago and try very hard to avoid flying out of range of land. If you take the short crossing and fly high you will only be out of range of land for a very short time. In my aircraft this is typically 90 sec. You are also over the busiest shipping lane in the world and the chances of a warship or a suitable boat being in gliding range is quite good. The risk for longer crossings, single engine, is mush higher.
Rod1