Generally, if you are a lighter person you can benefit of a shorter hull and vice versa if you are a bigger person you can benefit of the longer hull. But this it also comes down to your own preferences, what characteristics you like? How you want your ski to behave in different conditions? Even such a thing as storage space is one factor when finding your new ski. If you are 95 kg 2 m, yes your natural option would be the longer hull and if you are 60 kg 160 cm you likely choose the shorter. But anything there between you can choose depending on what characteristics you like. Of course if you are the bigger person choosing the shorter 54 hull it will sit slightly deeper in the water and opposite for the lighter person choosing the longer hull it will float slightly higher.