My personal experience is that if you want comfort, speed and control for freeriding in choppy open ocean, you´d be better off with a FREERIDE board rather than a Freestyle one.
Whereas I really, really, loooooove my freestyle board (it's actually my preferred one), I just use it for practicing my amateur freestyle moves. It starts planing quickly and has easy pop. Also, when combined with the FSW fin, it has easy sliding. HOWEVER, when I sail in open ocean and surf waves I am better of with a freeride or a wave board respectively. I feel the pure-freestyle board doesn't have the top speed nor the maneuverability to practice the good-old conventional windsurf style, and I hate gybing on it because it barely has any grip on the water.
Again, that is my personal opinion!!