hey MDickerson,
I can't really comment on the conditions in Sydney but I learnt on a 10m Cabrinha Switchblade in Perth and I'm just over 80kg's.
I found it a great kite to learn on, very forgiving and stable.
having said that I have tried the xbow but not many other kites.
a 12m should do you just fine for your weight.
best thing is to ask your instructor when you get lessons cause you will get lessons


they will have a good idea of what gear will suite you.