formula with freerace o race sail ?

[Windlover]

Hy everybody

For having the earliest planning (ideally 6-7 knods), is it possible to use a freerace sail with a 75% mast? I plan to use the formula board under 12 knods more or less (for now).
Has anyone tried a freerace sail on a SB '05-'06 with low winds?

I'd like to make the right choice

Thanks