Here is what I really think:
I do agree on the hierarchy of props.
Flow Arts = Poi, Staves, Hoops then the rest
Juggling = Clubs, Balls, Rings then the rest.
I think since we are mainly talking about prop manipulation, the movement of feet might be another story. In my mind, theres 3 categorization, spin/ swing, contact , toss.
So if you look closely to those 3, spin/ swing heavily belongs to the flow arts. It has to, think about the biggest contribution, the antispin and the buzzsaw. It was not like the flow arts created it, it already has been there for centuries, its just the flow arts popularize it.
Contact, its a blur area between juggling and flow arts, cause the difficulty is high hence more towards techy / juggly but then theres movement of body or the sense of kinetic awareness, more hollistic, flow arts? It also depends what style of contact, rolling, or wrapping and then it falls into either category?
Then comes toss, traditionally the whole world knows toss = juggling.
But here comes the catch though, theres the catch though, does that mean from a poi spinner once you start tossing poi you are entering the juggling realm?
Or a juggler once you start adding swings, buzzsaws and even the amazing antispin you are entering the flow arts.
Or to get even more confusing, swing, antispin and throw with 3 clubs?
Or strictly work on siteswaps with 3 poi?
But thats the beauty no? Like if you are the king of siteswaps, or the king of antispins its like ok. But then once you are the king of antispin, contact and throws regardless of props then we are talking. Then you have shred all labels and have entered another dimension?
Chew on it, let it digest.