One huge advantage of (original) dutch subs:
They were very similar to U-Boats!
They even used G7A torpedoes (yes, the dutch actually used german torpedoes to sink japanese ships:rotfl
Ok, the G7A had a long and useful life anyway, was used in the postwar german navy and a lot of NATO navies until around 1970 at least.
I suppose the fire control procedures and internal arrangements would be similar.