Deliberately tried a number of boards of different sizes, shapes and
types, here are some of the findings I found (some of them are well
known but I put them here anyway):
1- Small boards need more power, large boards need less power. So for
the same wind speed, use larger kite for a smaller board and smaller
kite for a larger board.
2- One can go for a board as small as one like up to a point where one's
leg get tired too soon - cannot handle the kite power for a very long
period (for me its a 120 cm long and around 36-38 cm wide)
3- One can go for a board as large as one like until it becomes too
clumsy (for me its the FOne 230, 230 cm long, 50 cm wide)
4- Thinner rail is more efficient than thicker rail for edging.
Sharpness has some impact but not as much as thickness.
5- Longer rail is more efficient for edging
6- So short boards should have thinner rail and long boards can have
7- Fins are not needed on bi-directional boards (regardless of board
size, shape and rail type)
8- Directionals are better for variable wind and light wind conditions
9- Shorter boards are excellent for jumping
10- Longer/larger boards are better for light wind