RE: Formula Boards
I have had F155 and now have F147.
It is easier to sail in all respects. But compared to F155 much more upwind-downwind oriented. Optimum finsize 70; the 58 will not provide enough lift so the board will feel sticky.
It is much easier downwind. I have done 51.2 kmh peak speed on GPS with it.
Beam-reaching will feel less natural on the F147 compared to F155.