Nobody else answered your question so I will try.
I have never heard of the skysurf foils, can you tell me where I can find
more info. Different kites have different power outputs.
In any case a 6.5m foil is good to start with on your board, but you will
need more than the 11 knots you mention. Once you are good, then 11knots
might get you going on your big board, but during learning it will be
easier if you have more wind.
A new kite will not necessarily help. Try to get the basics with your
current kite and then once you can get up on the board and going back and
forth, then you probably want to consider getting some sort of kite with a
depower system. A depower system will make it easier to learn to go upwind.