Thanks again everyone for the advice, just a quick update.
The trip on the Kitesufari was great, I put a post up in the general forum if you haven't seen it.
As it relates to my quest for a good kite size;
As with everything, it is experience that counts and having the recent 4 days of solid kiting that I did, was invaluable- it was a massive confidence booster.

I started off with 8m Cabrinha Switchblade 2010 & when my confidence was up, it was blowing a gale so I wasn't sure how I'd go with the bigger kite, I made the change to a 10m Cabrinha Switchblade 2010.
The 10m was not a problem at all; it was a lot of fun, I didn't have any problem controlling it at all & was using it fully powered the whole time.
So now I'm actually leaning towards getting a kite in the 10-12m range & two boards, one smaller for when the wind picks up a lot.
What do you guys reckon, surely that's the same as getting a smaller kite & two boards, one bigger for when the wind is light?