The diff between free formula like I150 or JPSLW and latest in formula boards:
Formula boards - best in yearly planning and upwind/downwind angles, using apparent wind you can blast thru
most lulls/wind holes, you'll need large fin (70cm) and larger race sail to take advantage of their potential,
They are easy to ride, but it''s a long learning curve to perfect it, I see it as a good thing, since you would
not out-grow the board or get bored with it...
Free Formula: easier to ride and dial into, less physical, requires smaller sail/fin but will not give you the same level of performance, better suited for reaching and BAF