Flow is a word commonly used in FMA. There it's considered a high part of the art. Flow is also used in Tai Chi, Aikido and many other arts. Just a few questions to think about:
If flow is considered more effective in some systems than others, why?
How much of that is the mindset of each practitioner, how much the training? How are those related?
Is flow always "with" or can it be "contra"; can one flow against an opponent?
Is flow internal (intrinsic) or relational (extrinsic) or both?
Are there degrees of flowingness, or is it an absolute; you either have it or you don't?
Is flow different between soft and hard styles or is it ultimately the same experience, just different kinesthetic language?