Hummingfrog,
Apart from taking twice as long, ie to winch them onboard and then cross-transfer, you would have to assume that the vessel is not in the final stages of sinking or on fire - otherwise the lifeboat might as well fish them direct from the sea when they abandon the vessel and save all the effort of winching them!
I don't think the SE performance of the 139 is as good as dear old Walter, and thats using the marketing figures from the Agusta website
.