I think that Ken indeed made a very good point.
How many more sailing days will you get out of such a board.
Where I surf, I can choose between lake or open sea.
The best spot for me with a formula board is the open sea, because if offers in summer time a lot of days with steady 8-12 knot summer breezes.
Because I can only surf at weekends or holidays and this only during half a year (winter is much too cold with us), it probably increases my sailing days with 30%, which is a lot.
Often, these "formula" days are also high quality sunny days (of which we don't have too much, where I live) and it are days that I can take my family with me as well.
On lakes with a lot of lulls, I don't think that a formula board is very interesting.
IS87 / IS101 / IS122 / US147