I'll put my opinion, though I haven't seen or rode any of the boards mentioned.
Me I like the Kona and would give Exocet their dues on that one!
It is a tough choice whether a Kona or Serenity would be my ride as both are very nice, but with two very different applications. I like the serenity, but you can't find good images or info which is a shame!
I am waiting for www.windsurfjournal.com
to get one as they are the best online website I've seen.
So note to Starboard.... more pictures and details! I want a Serenity... but need more info comparing it to Equipes, Div 2's etc!!
p.s.. Hows does the Serenity work with a paddle and used like a kayak?