We conducted one of many Terry and Deena Memorial Boat Tours just the other day with someone thinking of buying an Amel. Without your hospitality in Honolulu--right after a long crossing--we might not have ended up with one of these amazing boats! Karen has become a true Super Maramu evangelist.
The isolated ground system that Amel uses is unusual on a fiberglass boats, but is very common, even necessary, on Aluminum boats. Given that aluminum boats are a lot more common in Europe, I'll bet the Fidgeoboat factory in Italy has a good answer.
Since I didn't install our keel cooler (the previous owner did) I cannot say if there was something special about the installation I can't see.