Don't think twice, the Serenity is a great board for non-planning conditions. From 2 to 7 knots it's amazing! Just hook in and let it go gliding smooth, fun and fast!
Check this video made 2 days ago in a late afternoon session here in Brasilia. 3-8 knots:
http://www.youtube.com/watch?v=aVqpsr289es
Marcello