Speaking as a mech rather than a pilot. Surely the lighter sea state floats on a Puma series would not be the factor as far as settled in the water stability goes. In two events of Pelita Air Service Puma landing after emergencies, the helicopters sat in the water with water about ten centimetres deep in the passenger cabin.
Aerospatiale said this is a design feature, and gives greater stability in once settled in water. I suppose this makes the assumption that the cabin doors are not open as waves riding through are going to definitely affect that small amount of added stability.
If anyone has a long memory one was at Matak Island in Indonesia about 1980 pilot Ted M and Dick R, same year for the one Aceh, Sumatera. Pilot Wolgang S and Mech John B.