Hi Rob, first thing Mamba 2023 shapes are the same as 2022. For your weight of 70kg and 3.7-5.0, I would not take a Grip 81, that would be too big, especially for strong Mistral in South of France - either a Grip 76 or a Mamba 78 - choice between these 2 is that the Grip will perform better on the very strong days/with smaller sails and in more DTL conditions. The Mamba will be better for South of France conditions for sure, suits your weight and the sail sizes. So unless you are doing regular trips to more side shore locations/waveriding is your focus (then Grip 76), I would go for the Mamba 78.