Re: Repowering with an electric engine?
If the boat is big enough, say 60' or larger, a hybrid could make sense. But not for all the reasons you mention. The best location for weight is above the keel. Not everyone likes an engine or generator there, particularly in a smaller boat. The ideal location for sound is aft away from the main living area. And as you have said it is expensive compared to a standard engine installation.
Living aboard in Victoria Harbour