Kitesizes for CapeTown has always been a tricky one where a lot of "firsttimers" go wrong taking too big kites, let me give it a shot at explaining:
The thing is, about Capetown "winds", around CT and down to Cape Point, that there is not always wind, dont expect that
We have been lucky and it has been windy 85 % of the days down there late january/start february (say 12 out of 14 days), but you can also have rain occasionally, or no wind, or almost no wind from the right, or okay wind from the right down near Cape Point
And then, WHEN its windy from the left, fully sideshore a bit off sometimes, it will start either quite early, but in most cases totally calm in the morning and before noon, perfect for clean surfing, and then just after noon it starts to pick up.
The thing is, it picks up so fast the next hours, that you will not be able to use a bigger kite very long.
It continues to pick up and usually a lot of wind from 16 to 20 when the sun has set, and it does not stop again, till late night.
This is the very reason why big kites usually does not make sense at all - either way too little wind, or it picks up so fast that before you have rigged your "bigger" kite, it gets too big.
Only for hydrofoiling in almost calm, or dead onshore or wind from the right, bigger lighter kites could make sense, otherwise not.
If you go to Langebaan far up north, for flat water as said, it is different and can often be used, but not in and around CT in my experience
Peter