Hi guys! Thanks for your replies

I had another good sail yesterday and was starting to pull off my tacks and gybes in a 13kt wind...there was a big crew down at kymea so I borrowed a 210 litre board with a retractable and same size sail as mine-on that I had no worries on the turns (albeit with the grace of a mule).
After about an hour I felt like I had already out grown that set up, which confirms for me the idea buying a formula board is better long term...I know I'm taking a risk in terms of the fragility though, thanks for that warning. I go through surf boards like loafs of bread...i'll just have to take it easy just using smaller sails for now.
So I'm after a used formula set up if anyone know someone.
Happy sailing-Sam