GN, I doubt the gear was down for the ditching. Well hopefully it wasn't.
1 line of thought tho for off field Emerg landings on LAND tho is to lower the gear as it is a very strong component and will help absorb impact forces as it is possibly torn off by the impact. This means, hopefully, less forces to be absorbed by the fuselage/cabin area thus a greater chance of survival. Obviously every situation is different and requires a judgement call at the time.