I guess in colder waters it makes sense to try make the ship stand on water, which is quite difficult particularly in either glassy or choppy seas, but otherwise the flotation device only needs to keep passengers heads above water, but that then that makes egress quite interesting if the rotors are still turning. Some major rethink is necessitated on these flotation devices because being inverted under water appears to be one of the worst outcomes for the untrained.
This incident also reminds me of an R44 incident in Docklands Melbourne where the pilot jumped out of the helicopter and survived before it splashed into the harbour killing the other occupant who was also a PPLH. If anyone has a link to the outcome of that investigation please supply it.