jugofpropwash
1. to be honest. it would be IDEAL to have the lifevests on. It is true that boats are coming in and the plane is not sinking (quickly). But to add more safety in the case that the aircraft begins to sink rapidly, they would still float on the water even if they don't know how to swim.
In the case of people inflating there lifevests prematurely. That would totally depend on the person itself. Even if the crew was highly experienced and instructed all the passengers. Some would still be panicking in that situation and might instinctively react to inflate the vest, making it harder for them to go out of the exits specially the overwing exits which is smaller than the doors. and ofcourse if they do jump in the water which is very cold, hypothermia might kill them if the rescuers werent there to pull them out quickly.
2. In the case that there were not enough life rafts. I can definitely assure you that there is enough for all the passengers even at full load. The life rafts at the aft doors were not inflated and only the ones in the FWD doors are inflated. ( as you can see in the pic, they have no choice but to stay on the wings, since they cant use the aft emergency slides which doubles up as a life raft when detached from the aircraft)
