In my opinion - smash in 20 hrs to learn how to ride a 70cm raceboard- spend another 30 Hrs getting Ok around s race coarse in all wind condition - then spend another 100 hours to get as fast as possible around a race coarse- then you might warrant getting the best ( very expensive fins).
Personally I think a top racer could use any board or set up and smoke 95 % of the field with a combination of experience, skill & being very very fit.
Every board has very different riding characteristics and some like my Alex Aguera LW very challenging to ride as it has a super powerful tail outline & and has taken me 50 plus hours on water to get it working without killing me in massive crashes trying to ride at 100% in all directions at my current skill level - but now I love the board. Alex Aguera now has an new easier HW model to purchase & ride but that's another $2000 so I have to use what I got now and make it work.
I reckon get on water- put in lots of time - kite with as many others as possible - find a buddy with similar skill set and train together and eventually you will get faster.
From what I can see on water Damo & Alty are smoking fast on that board and fin set up. I still reckon Damo could smoke 90 % of race board riders on his Sector.
I have over 250 hours on a race board & still learn new things ever day.
Forget the board/ kite / fin questions & get riding - if you get to the Gold fleet in World cup Melbourne- the best rider who has best set-up for themselves & top skill set will float to top. AKa Johnnyheinekin - I reckon he could ride any setup and still be world champ.
JohnnoKeys. See ya all racing in Melbourne.