The best person to answer this would be someone like Mushipea Steve, who has been on the juggling/festival scene for a while.
[Boring mode]
I work for the National Trust and one of the properties I look after is Clandon Park in Surrey. The house has very strong ties with NZ - even going so far as to transport an entire Maori Whare (meeting house) from Rotunda (or somthing) to Clandon in one piece. Anyway, I got a chance to look at their family photo albums and they had pictures of traditional Poi being done around 1932 - I'm pretty sure they children would have played with poi and practiced with them in the UK before this too...
[/boring mode]
Another tricky thing is the difference between traditional poi which has been around for centuries and "modern" poi - using fire/glowsticks etc.
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Burner of Toast
Spinner of poi
Slacker of enormous magnitude