Davide has some good advice. I seem to recall he thought the Acid 74 was a bit big at first, but maybe he got used to it. A comment on that would maybe help: Do you now feel the A74 is easier in high wind than you did when it was new, Davide?
Freestyle: I'm not a freestyler myself, but it seems the good ones whip out their moves on pretty much any board in high wind. That said, the K86 will for sure be easier in freestyle, particularly in lighter winds.
Riding: I agree, for what you describe the Kodes seems better.
RRD fsw 80: I would say it comes in somewhere i between the K80 and 86, it wil feel a bit bigger than the K80 for sure. So your view of the "fit" of the RRD is probably in fact a great indication of which size Kode you should go for.
Also: the more "straight line backside B&J" stye sailing you do (relative front side wave riding) the less problems I think you will have with the 74 in high wind. It is for its size an extremely controllable board, just like its predecessor. They have for many years been tested as the most controllable in their class.