Funny, I had a Carve 145 and a Tushingham Lightning 9.4 too. I'm 97 kgs and clocked 28.9 knots with the 9.4 and +30 with smaller sails on the Carve 145. It's not a slow board at all, but it has to be sailed very much on the aft of the board. It's quite an early planing combo too.
I used to hate formula too, but after switching to a F159 and a Tushingham Lightning 10.3 I must admit that they (the newer short designs, NOT the older ones) do have a lot of freeride potential.
They do reach quite well actually, they are fast, control is very much better than they look (100 cm wide with 70 fin). Cruising potential is HUGE and time on the water extended a lot if you live in a low wind area.
Only disadvantage is that some of them are quite fragile.