Hullaballoo
Its an airframe, fuel system and component issue.
The S-92 is heavier than the EC225 because of the additional "beef" built into components to satisfy 100% FAR JAR 29. Likewise, the AW139 is a bigger and heavier aircrfat than the S-76, same reason, 100% compliance means some areas have to be beefier. Ditto the EC175.
The S-76D cannot be fully compliant withot a complete re design so it will be mostly but not 100% compliant versus the 139, like the EC225 versus the S-92.
Its not possible to take a 1960s (Puma) or 1970s (S-76) evolutionary design andmake it 100% compliant. From good sources, the offshore version of the S-76D will be around 96% compliant.