I agree with Roger. The Serenity is an amazing board. It doesn't plane, but it really feels good and fast in less than 10 knots.
I used to have a formula board. It was great in 10-15 knots, but it was frustrating if there wasn't quite enough wind to plane, because then I would be going slow while struggling to carry a big sail. The advantage of the Serenity is that it doesn't need a big sail, and you don't have to worry about "will I be able to plane?".
Now I have a Kona. It's easy to ride, and it's fun when it's on a plane. But when the winds are < 10 knots I wish I had a Serenity.