edt, you are going to use it for foiling I assume, and maybe also tt?
But important to know if for foiling, as if, then the advice about a 21 m2 speed is useless.
If ONLY for tt, it might make sense for some yes, for many no, not even on a tt.
As I know you are (also) foiling, the questions must be because you want to foil really powered and jump, or use in on tt's also, for jumping.
Important for those answering this topic, but okay, you have already stated you are talking about Flysurfer Soul and maybe even max a 12 m2 so makes no sense to answer on other kites
Most have good intentions answering, but the OP was very specific about the kite, that was my point - except for the hydrofoil or not part edt, eventhough it does not matter regarding the powered question, and as you asked about a 12 m2, well, you dont have to know about foiling or not