Roger,
Many thanks for the direction! I had been going to head down in size to try for stronger breezes, so I will look for bigger instead.
I had my first try at the beach instead of protected waters on Monday, and was pleased to get up a few times

. 1m swell got in the way of easy starts, but once up I managed to get some runs in about 12kt wind. Certainly a larger sail will be great. More power is needed as I can't get enough lift in the fin to beat effectively, or get on the plane in those winds.
I find the GO 150 very responsive after my Windrush Storm 10, which is way longer.