Hi Vincent, you did not mention your FreeWave size? But generally a 78/75L sounds like the best option for your weight/sail sizes and conditions. Choice between the Grip and Mamba is fairly easy - the Mamba is great for almost all European conditions, plus reasonable DTL conditions, with a faster rocker and wider tail/straighter outline. The Grip on the other hand is also a fantastic allrounder, but excels in DTL conditions, whilst still being a good board for European conditions. So its really about how often you have real DTL conditions, is planing, speed, jumping, smaller flatter waves your focus (Mamba) OR you love DTL conditions and want to mainly wavered (Grip).
That said, both boards will work well in both worlds, but tend to be slightly better for each extreme (Mamba onshore to small waves dtl) (Grip dtl, bigger choppier waves)
Coming from a Freewave, you would probably like the Mamba more for it's instant planing, more similar to the FreeWave style rocker. Grip 82 is for sure too big for you.