Increasing to the higher gross weight is a lot more then just some structural upgrades. There are many components that the life reduces and part numbers change. So components on the lower gross weight aircraft cannot be used on the higher gross weight and vice versus. That is a big increase in costs to operate with the higher gross weight regardless if you actually operate the aircraft at the higher gross weight. If you have both types in your fleet you have a lot of expensive parts to keep in stock that can only be used on the one type. This is the main rotor parts , main rotor servo´s etc. If you plan to upgrade your aircraft do your homework!