Hi jrobinson,
April is notoriously unreliable for wind in Perth. Last seasonwe closed the school in end of March due to lack of reliable wind, although having said that, we have had seasons where we kited into late April. This is for Perth though. The wind should hang around a bit longer the further you go north.
Not sure this year, the weather is a bit wierd and the water is unseasonably warm. I think we'll be right for March, not sure about April, I feel it may just drop out all of a sudden.
These thoughts are of course all coming from WA riders, as an East Coaster, you'll be happier with wind we probably wouldn't bother with.

I'd bring a 12 and a 9.
DM