My own impression on the C4 models are a bit different from Walrus'. As I have been told, the models have these characteristics:
Falcon 25: long blade, very soft, for beginners
Falcon 30: long blade, normal stiffness, 'normal freediving' fin
Falcon 40: long blade, very hard, the records fin
Falcon 80: extra long blade, very soft like the 25, mainly for weak-legged people that will get the extra power from the bigger blade surface
I believe Pelizzari made use of the Falcon 40 for his attempts. With regards to the pics of Murat, I think it's only for the sake of the camera, I doubt that he'll be using them for anything official. Even on the pics you can see how the blades fiercely over-bend, which is making you loose power-momentum in your dive. With my impression of Murat's level of stamina and his level of knowledge, I don't think he's using the 80 blades for anything serious. Ther 40's have proven much better (excluding monos).
Chris Engelbrecht, Copenhagen